If that were true, it makes the epidemiological case for an aspartame link clearer, because you'd simply be able to compare cancer incidence between countries by aspartame consumption and see the evidence. It's the most studied additive in the history of the food industry, and that link has not been found.
It turns out measuring aspartame consumption by country is not simple and that there aren't good sets of equivalent studies across regions to draw from. I browsed some papers in the National Library of Medicine[0] and it seems like, at least as recent as a decade ago, it's generally accepted the USA has a higher intake than the rest of the globe, by 15-25% per capita, but it's hard to know for sure.
I agree there should be an epidemiological case for a link, but alternatively maybe the link is that there is no strong link to cancer.
Everything in moderation, as they say.
0: search "aspartame intake", I can't easily cite anything right now.