I think perhaps your "problem" is the "better quality products". You see, American-style canned black olives are pretty flavorless (call it "mellow background flavor" if you wish) whereas imported Greek or other Mediterranean black olives have a pretty assertive briny flavor (or, if they are the oil-cured type, a somewhat bitter flavor). Apparently, your pizza source has started using the more expensive imported olives.
I do feel your pain. I make a mean putanesca sauce, I think, but I like lots of olives in it. If I used the imported ones, as most good cooks would, I think the amount I use would overwhelm the sauce so I use the much blander American ones from a can. It may not be "gourmet" but it suits my taste buds. Since you can’t dictate the ingredients in the pizza, I’m not sure what you can do but you might mention your displeasure to the cook. Maybe they’ll go back to the domestic ones (or offer both–patron’s choice).