I don't drink, and rarely have the most expensive entree, and hate it when people try to figure out the exact perfect split of a check. It somehow always takes longer than it should, if we're all friends here making roughly the same amount, let's just split it evenly.
Dining out with friends isn't solely about turning dollars into calories.
Considering everyone has a very capable calculator in their pocket, notebook, and camera in their pocket, it's quite easy to figure out your share. You can simply note how much your meal and drinks cost, add the tax and tip, and drop it in the middle as cash at the end.
If you go out often (2+ every one to two weeks), don't drink alcohol ($10+ per drink in NYC/SF, prob even $15+), and you don't eat meat (+15% I bet on average for a dish), and don't get dessert ($10+), why on earth should you be putting in an extra $20 to $50 more per meal? Why would I accept that from someone I consider a friend, or a guest?
The theory behind splitting the check evenly is if you go out a bunch of times it all evens out. But that doesn't happen if you split the bar tab over non-drinkers.
Dining out with friends isn't solely about turning dollars into calories.