Not if you're yearly income is less than $12000, and I don't think they'll go after you even if you make $100 thousand, because you still won't have to pay any US even if you do file (most countries have agreements with the US to avoid double-taxation below a certain amount). I know a lot of American citizens who live permanently in Canada, and not all of them file US taxes, including my mother in the decades she's lived in Canada.

Technically, by law, return is required for any income over $0.50, no taxes till world wide $12000(US+NonUS) or $107000 Foreign/NonUS income, but still, IRS expects a return filed. In practice, yes, not much problem.

There are advantages to filing even when it's not required. Oddly enough, the US government still paid me $1200 + $600 of COVID economic relief (auto-deposited to my US bank account) even though I haven't lived in the US for many years. I didn't think I'd be eligible, but apparently I am (just in case, I haven't spent the money yet). It's weird that they gave the money so freely.

The money was given out pretty indiscriminately (on purpose, they didn't want vetting to slow down the process). There has been massive fraud, but on the otherhand the benefits made a real difference to a lot of people at a time when that mattered. I think keeping the money "in escrow" is a good idea. I know I'm above the income limits for some of the benefits, but still got them. I expect I'll need to pay them back just as part of normal tax fillings.

Unconditional benefits are less susceptible to fraud because there aren't conditions to evade. They're also easier to administer and are generally progressive, as a fixed universal benefit is more useful to poor people than high income people, due to the diminishing marginal utility of most benefits. Taxation, as you say, does the rest.

Not a professional, but as long as your 2018 or 2019 return falls in eligibility box, you got money, & its good.