As someone who was on a condo board...
The issue is more than just choice.
How easy it is will depend on the building and how their broadband (cable) network is laid out.
Builders will always find the cheapest solution even if its not the best.
We were approached by Comcast to do a building wide deal. Some residents wanted to offer basic cable as part of their monthly assessments. When you looked at the deal, you notice a few things...
1) Lock in period. Usually a 5 year contract. (We limit our contracts to 2 or 3 years maximum depending on the service.
2) Pricing. When you have someone who only wants basic cable, its a great deal. If you want some premium channels or packages, you end up paying more.
3) The condo association was on the hook for anyone who didn't pay their monthly bill to the cable company. So if you got basic and then added premium packages, and you didn't pay, we got stuck with the tab. So we would become the cable company's bill collector.
4) Choice. There's a difference between cable and satellite packages. Some people moved in and already had their own Direct TV box. So they wanted Satellite. Others wanted Cable. So you end up pissing off a large majority of owners if you do an exclusive deal.
What we did find is that most now have Comcast because of internet.
We did also let in Century which is a competitor because some wanted to go with them. They too wanted to get an exclusive deal. It didn't happen and they agreed to our terms and did the install. This meant drilling holes in the floors of the telco closet on each floor in order to run their own cable. The net result, few switched and it was a loss for them. (They still provide service to some residents. )
Note: This is a Condo.
Apartments would have the same issue, and its up to the landlord to decide what to do. Depending on the building size, they may offer their own plans and have a deal w Comcast or the other major cable providers. They will do what they want and what is cheaper for them.
In certain markets... you care more about location and price versus your cable provider. If you don't like it, you can cut your cable and just go with internet and over the air broadcasts, which actually have better quality pictures.