ster wrote:
maybe he can get away without flushing- i've seen plenty of public toilets that haven't been flushed in my time

That is a BAD habit! I USED to treat toilets like a bomb! I went, flushed, and moved away. NOW, because of so many unflushed toilets, they flush THEMSELVES! HOW do you move away if it flushes while you are on it?
I would have designed them to work like follows:
1. Is a person within 3 feet? If not, keep checking.
2. Have they moved away? If not, keep checking.
3. While waiting for 20 seconds, check to see if they came back. If they did, go to #2!
4. Was the toilet flushed? If not, then flush it.
5. Go to #1
Average flushes on a toilet I use? ZERO! Maximum flushes per user? About ONE! I usually flush MYSELF!
HERE is how most are designed:
1. Is something within a certain distance? If not, keep checking.
2. Have they moved past a certain point? If not, keep checking.
3. flush toilet.
4. go to #1
Average flushes on a toilet I use? FIVE! Maximum flushes per user? I have NO idea! I have been in places where they just keep flushing. With my bag and all, it may flush two times while I am merely getting out!