I understand your point, but I think a lot of places have realized that customers don't like carrying change, so if there is a tip jar, the customers may drop the change in the jar. Thus, the customers don't get stuck carrying unnecessary change if they don't want it and the employees get a little boost to their income.
I do agree though that it's strange to see them popping up everywhere. If it's a food place or something, I may give a dollar but it sorta depends on my mood.