Something really strange happened a few years ago in the realm of tipping. Over the counter food preparers and cashiers started putting out tip collection jars, baskets, cups, etc. What’s that about? Has it ever been tradition to tip the cook? Not at all. The reason servers (waiters/waitresses) get tips is because they provide a service as the focal point between the customer and restaurant and its staff. When you tip a server, typically a portion is re-tipped to the host/hostess and the busboy separately. If there is no host/hostess, the server usually doubles as the host/hostess. If there is not busboy, the server has to double as a busboy. In these cases, the server keeps the portion that would normally be given to another person fulfilling those roles. In any case, these are the only three positions in a restaurant that can expect tips. Cashier is not tipped. The cook is not tipped. The owner or manager is not tipped. Basically, if there is no server, there is no one to tip.
So, why tip over the counter food preparers? You’re not supposed to. This is even an IRS relevant matter. If a tip is expected, the person receiving the tips must pay tax on 8% of the sales that person handles, whether they receive the tip or not. Comparatively few people tip over the counter, so this means those cashiers and food prepares are required to pay tax on money which they have not hope of receiving. The responsible restaurant owner should not allow tipping jar placed on their counter, and should even have a no tipping policy. This saves the staff from paying extra taxes, and saves the restaurant from the headache of having the paperwork and labor to track tipping for the IRS.
I tip generously. This is because I live in Silicon Valley, were the expected tip is 15 to 20%. Where service is reduced (you take your own bill up to the cashier, or you seat yourself), the tip may be reduced in kind. In those cases, 10% is acceptable. Where there is no service, there is no tip.