Scrunching up my face trying to figure out how to respond to this...
I think you are right that a lot of the wine which people consume, the mega industrial mass volume stuff sold in supermarkets, is a bit sweet, although often not by a lot--Josh and Bota Box, two of the biggest brands, have like 5-10 g/L of sugar. Stuff like La Marca Prosecco and Barefoot Pink Moscato is noticeably sweeter.
However, in general, I don't think it's fair to say "wine is sweet". Wine in general is not sweet outside of certain styles that are intended to be so. If you grow grapes, crush them, and ferment them, the fermentation will generally run until the yeast run out of sugar, leaving only trace amounts behind.
I've noticed that a lot of people who don't have that much experience with wine will tend to mis-identify things as sweetness when they're really noticing some other aspect of the wine.