You must live in a weird place, I've never once had a waiter even react to splitting a check. In fact the majority ask us first (especially when it's multiple couples at a table).

A friend of mine says typically when she splits a bill, both payees will assume the other is a crappy tipper/don't want to tip less, so they'll both tip a higher percentile and she'll occasionally get 1.5-2 times the tip money, so when people ask her to split a bill she just hears more money coming.

Purely anecdotal, YMMV, etc. etc.

EDIT: I'm curious if downvotes are due to people not wanting wait staff to get bigger tips or if it's because wait staff in my area don't gripe about splitting bills? I never expected this comment to cost me karma, but such it is.