I feel the same way about people who salt their food before tasting it. As for the pepper, I usually turn it down, as it tends to be on the table or easily procured from the server who asks "how's everything?" as I am chewing the first bite.
I'm just thankful they don't come 'round squirting Sriracha all over the table.
I'd say that part of it is that the appeal of a tiny bit of extra service goes a long way in determining a tip. Another thing to consider is that while black pepper is cheap, a good pepper blend is less so, and leaving shakers on each table to be refilled would probably result in more expense over time than making the pepper less available. Possibly most relevant is that all pepper grinders are not made equal, and the ones restaurants could afford to put out on a table are far more cheaply made (and less effective) than the giant ones they buy six-or-less of and give to their waiters, which have mesh filters and heavy, effective blades, and they would rather use those, because crunching down on a whole peppercorn that slips through a bad mill can wreck your palate like few things can.
Also, why pepper on salad? I've never understood that. Pepper on steak or another hearty entree, maybe, but why would I want a fresh, crispy salad with a variety flavors from the vegetables, dressing and other toppings covered with fresh ground pepper?I'm not a big pepper fan to begin with, but it's never made much sense to me.
If the food hasn't been properly seasoned by the cook, my tossing a few grains on top of it isn't going to do anything. (Not to mention that raw salt tastes horrible.)
A long time ago, I read a very funny monologue where this girl said she was perfectly capable of peppering her own food; if you wanted to help her out, you should pour her catsup!
Ha, it's Ketchup. I really thought it was spelled like that, apparently not - maybe it was at some point?