The fact that government has imposed itself into areas where it does not belong does not make it right.
“If individual flushes put a similar strain on the sewer system, you’d have a point. “
They do, by reducing the amount of water that has to be imported and the amount of waste water that has to be treated, it all helps preserve the infrastructure.
There are reasons why pipes (like roads) have to be replaced and that includes the use they receive, but a treatment plant for instance can really benefit from a sizable reduction of unnecessary input.
As a plumbing contractor I am well aware of how fascinated people are with their toilets, but are you aware that your refrigerator is much more regulated than your toilet? How about your stereo, or your TV, or your furnace, all manufactured to strict government electricity usage standards, electricity use is more of an issue with the government than water.