That is WAYYYYYYY to simplistic way of looking at it. I can think of 3 different ways they can make more money that your model does not cover.
1) In general - people like bundling so there is one bill. Offer bundling and there is a VERY good chance that MORE people will sign up for service than without. End result - more customers = more money.
2) Bundles are cheap initially - there are plenty of bundles that look fantastic but actually are good for X period then go up. Not all bundles do this but they are out there and I would bet a paycheck that TW does this often (mainly because I know they do this since I live in a TW area). People don't realize the price spikes and they decide it is more hassle to drop everything and stay on (or they get a small discount if they complain but the overall total is still higher than the promotion price). End result - more money in higher billings - all they need is a relatively small amount to remain on the higher price to make it worthwhile.
3) Some bundles actually are more expensive and separate billing but passed on as being better. People don't do their home work and pay more. End result - more money.
Companies are there to make money - everything they do - they do to make more money. Even if they LOSE money on some items to get you in the store - most people will buy other items to make it worthwhile on the whole. They don't have to make more money per person or for every individual item they sell. They just want to make more on the whole.
If they can bundle a couple services and GAIN 100 new subscribers they did not have before and were not going to get - that is more money they make.
There is an entire arm of statistical analysis of what blend of prices a company needs to make more money and make things worthwhile. If bundling did not make then MORE money - they simply WON'T do it. Their stockholders would not stand for it because the alternative is they the same money (stock likely goes down - less money for the company) or they make LESS money and the stockholders will not tolerate that and they stock price will fall.
If bundling does not make them more money - they will simply stop offering them.
»www.enotes.com/bundled-g ··· services
This link is old but it explains a bundle that was not at a discount:
»www.techdirt.com/article ··· 64.shtml
With that - I am out of the thread.... Good day.--
"It drops into your stomach like a Abrams's tank.... driven by Rosanne Barr..." A. Bourdain