That is a poor comparison in my opinion.
Preparing and delivering the food actually costs a relatively high amount of money (price paid compared to cost to prepare and deliver). For an ISP, once they have all of their infrastructure in place, it costs them pennies per customer per GB to deliver that data and the data itself doesn't cost anything since they are just the conduit.
A better comparison is that the ISP is a company that manages the piping for you to get water. You pay a arbitrarily high price dependent on the size of that pipe. Now, this company doesn't create or manage the water (as much as they might want to), they just manage the infrastructure for getting it to you.They then decide to also start charging you for the amount of water that flows through that pipe.
Does that make sense to you?
Don't forget that this company receives millions in federal funding and they also wanted to charge the water making companies for being able to use the pipes.