AFAIK if you live in a country like Canada with higher taxes you still have to file to maintain citizenship but you end up paying zero since you can deduct what you paid in your home country.
This would apply to people relocating to countries with a lower tax base. In that case you have to renounce.
There isn’t always symmetry in the tax status of various elements. The US doesn’t recognize Canadian Tax Free Savings Accounts (similar to Roth IRAs) so you can’t benefit from them without being taxed in the US.
You can still get caught out. Taxes in the UK are generally higher than in the US, but Boris Johnson still got hit with a US tax bill when he inherited a flat in London.
Deductions vary greatly between jurisdictions. Capital gains taxes vary greatly, tax-sheltered savings accounts may not be recognized, certain rollovers programs probably only exist in one of the jurisdictions, etc. None of these people renouncing their citizenship just make straight employment income.
This would apply to people relocating to countries with a lower tax base. In that case you have to renounce.