Current channel distribution is not a monopoly at any level, except perhaps one. Syfy channel is only provided by one provider. You could say they have a monopoly on their content--just like you could say Nestle is the only one to make Nestle chocolate.
But there are several people making chocolate. And there are several people making content (with a lot of overlap.)
So channels price their content as bundles (not a monopoly yet) and sell their bundle at roughly the same price to every distributor. Still not a monopoly and not collusion.
Then the distributors have to distribute the content to everyone. Just as in your supermarket example, the costs run about the same (in large number aggregates.) You'll find that some areas have less expensive cable costs and others have much higher--because of the market area. No collusion is necessary to explain this.
No monopoly, no collusion. Just normal market factors.
That's the smoke and mirrors the system leverages. By themselves nothing is a monopoly. Taken as a whole, it is a monopoly.
If it weren't a monopoly ESPN (or any other channel) wouldn't be able to demand that each service provider has to include their channel, and pay their ransom, for every subscriber.
You have to pay for the overhead to supply the HBO Bundle. When you walk into the store, each item pays for a part of the store, the transportation, the storage, and the shelf the item uses.
HBO is not priced in quanta that can pay the transmission overhead. Supermarkets know that each trip you'll buy different things and overtime you'll pay for the overhead. Satellite and Cable are based on a model that have fixed costs bringing content to you whether you use it or not. So when you use any, you need to pay for the overhead.
Then you can add extras on top. Completely different purchase model.
There is absolutely no reason why TV services can't do a la carte (not necessarily to individual channel granularity) and still get their base infrastructure costs paid for. I have cable internet but not cable TV. I pay a cable "access" charge every month. If I had cable TV then that access charge is included in the TV subscription.
TV services could just as easily have an access charge and then discount it in tiers as the total value of the purchased a la carte (again, could be a la carte of mini-bundles of related interests) increases. As soon as the subscribed services reaches a certain threshold the access charge is gone. They already do this with the first receiver. It shows up on every bill as a charge and then a credit.
Current model is only this way because the industry wants it.
Because every service provider operates in the same way it is effectively a monopoly. You have 2 choices: pay one of them or don't buy TV service at all.
It's a model with increasingly ridiculous costs to consumers and it's going to burst at some point.