50

a day to house a prisoner? Let's see...
That's 18,212.5 (I multiplied by 364.25, to account for leap years) nuyen per year per prisoner.
The very
minimum you can pay each Lone Star officer is

24,000 a month. This is the bare minimum, because with anything less, he won't even be able to make a Low lifestyle. And like hell anybody's going to work for so little money he has to resort to squatting part of the year. Especially in such a dangerous occupation of prison guard. So let's double it to 48,000

.
Now, assuming Lone Star simply relies on their own High-Threat Response Teams to put down riots, the prisons could
maybe sneak by with one guard per twenty inmates, but that's only if you like letting the prisoners basically run the place, just being unable to leave. This is just straight muscle guards, not specialists like mages (you're gonna need 'em, and they cost big nuyen - like hell any wage-mage is going to risk his life daily with prisoners for less than he could make doing research with a megacorp, or as a Shadowrunner) or security hackers and spiders rigging the building.
Now, that's a constant cost, and remember, you need someone on shift at all times. So even if you take an enormous risk and run twelve hour shifts, that's two guards for every 20 prisoners, and round up to 2.5 because you'll need swing guards available to fill shifts, weekends, and if someone just comes down sick.
So, twenty prisoners earn you, as a baseline, 364,000

, and the guards alone cost

120,000 of that. That's about a third, on guard salary
alone.
Now, you have to provide for maintenance - of the facilities, of the security units (drones, cameras, and the like), guards' equipment (their riot gear, equipment, etcetera). Bear in mind, the less guards, the more the prisoners get away with, in terms of trashing the place. The Chronicles of Riddick: Escape from Butcher Bay is a really good example of what a Lone Star prison is like.
At the very least, the facilities must be livable. If they get too bad, the prisoners
will riot, and that will mean an HTR team will be called, and that not only means extra costs (HTR teams don't swat prisoner riots for their regular pay, bubba), and it also means the UCAS inspectors are coming down to see what happened, perform headcounts so they can downrate your pay, and so forth. So, riots are costly, you want to avoid them.
So, we'll assume each prisoner is living a 'squatter' lifestyle. 500

a month, they cost 6K a year to house. That's another 120,000 a year off of those twenty prisoners, and that's going to have the inmates really pissed off. Youch.
And then we get to the fun part - medical care! Maintaining a prison at the minimum lifestyle conditions livable without the prisoners cannibalizing one another and waging internal prison warfare daily, the prisoners will still be angry. Gangs will form along any lines imaginable, and they will do battle for whatever luxury can be found, from (most likely) smuggled drugs and beetles to (very unlikely) a couple of bunraku tossed into their cells by the guards to placate them. (though not entirely unbelievable...)
Hospitalizations cost

500
per day, and if they somehow get really, really tore up but still are breathing they cost
a whole grand a day. Okay, let's suppose that over the course of a year, those hypothetical twenty prisoners are going to spend forty days recieving hospitalized care - an average of two days in the hospital per year per crook -, and ten days recieving ICU care. That's another

30,000 - not as much as most of the rest, but still noticable.
So, let's see.
Profit (yearly) per 20 crooks:

364,000
Expenses (yearly, basic) per 20 crooks: 270,000
Total profit (before catastropic costs):
94,000!Good grief! You're making only 94K profit per twenty crooks, and that's before catastrophies?
And there will be catastrophies. Major fights will happen, inmates will be killed, HTR will be called. You will lose the money for the inmates who die, you will be fined per dead head by the UCAS, who will come in and do a body count, you will have to dole out combat pay to all the guards and HTR teams who participate, you will have to replace drones, cameras, prison equipment, etcetera, that got trashed on the way. Oh, and speaking of dead heads, you'll have to pay out compensation to next-of-kin for dead guards - and there
will be dead guards, and you'll have to hire and train a replacement. One good riot, and you very swiftly run into the red. And this is barring a real catastrophie, such as a Shadowrunner somehow being incarcerated with most of her abilities intact and effecting his own escape over the dead bodies of most of your onsite guards, or a Shadowrun team effecting a break-out of a colleauge or a target. Nor does it take into account that mages and security riggers are definately not going to work for less than a middle lifestyle.
All in all, it's very easy to see the Star quietly organlegging (and secondhand cyberwaring) any Shadowrunners who come in, as well as organlegging the majority of the trolls (I guess despite the image, the metatype isen't really given to crime), and especially physically fit specimens who come in. Not only are they an instant cash injection (prime organs means prime price, and 'ware is very, very lucrative, especially since there's always the chance you might get to secondhand the same piece of 'ware more than once), but it cuts down on the violence and general mayhem inside the prisons.
Oh, and Shadowrunners can't exactly bust out a colleauge who's been carved up and apportioned out for a profit, can they?