It would be nice if someone can find out what brand they REALLY are since Wegmans is a supermarket and they aren't in the business of growing and canning tomoatoes.
You are correct that it is unlikely that Wegmans packs their own tomatoes, but there is more than one other possibility. They might simply be a national brand with a different label, but that is probably not the most likely scenario. Few national brands like to pack their flagship spec under another brand. I can't speak directly to tomatoes however. Other possibilities:
► Wegmans might have enough volume that they could write their own spec; in which case they effectively are in the business of growing an canning tomatoes - they just outsource all the work to other businesses. I tend to doubt this is the case.
► Often PL packers will offer several different quality levels of a particular type of item. The customer can pick the price/quality combination that best fit their business model. In the business I was in, this was the most common.
► Some PL customers are strictly focused on low cost and will allow a much wider range of tolerance in their spec - effectively taking whatever you want to put in their can in order to get the lowest price. This doesn't necessarily mean the product will be bad - rather that you never know what you are going to get. They may be the best tomato you ever had today and total crap tomorrow. Sometimes you will see this in the lower-level brand of PL customers that have multiple brands. Bear in mind that this really only works for minimally processed items like tomatoes where the spec is around the raw material and the ingredients and nutritional info doesn't change with the quality. It doesn't work with most processed foods because the ingredients and nutritional info vary widely with quality.
I never understood why someone would trade price for quality under their own brand. It's not just a can on the shelf, it'as also the name on your store. I should note that there are retailers that go the complete other direction. I worked a lot with one particular retailer that before they would pack anything under their flagship brand (which was also the name of their store), they put it through consumer panels, and it has to beat - not tie, but beat - the national brand leader. It was not uncommon to spend a year or more developing an item for them.