Probably a good portion do it unintentionally, but the ROI would be really low: “hey Mr. Mechanic, you made a mistake and owe us $17”

as opposed to “hey Mr. Hedge Fund Mgr, you made a ‘mistake’ and owe us $17,000”

Personally? None, at least none that care to admit it.

But when companies like Amazon or Apple can get away with not paying taxes, then that means that the rest of us have to pay to pick up the slack.

The only thing that comes to my mind would be tipped service staff not reporting tips as income.

Tax evasion, no. Fraud oh yeah most definitely. This year's current tax scheme is claiming the fuel tax credit, previously it was self employment COVID relief credits. The IRS is going after them and don't trust tax preparers who say they can get you a much bigger refund. They usually are committing fraud.

You'd be surprised. Small business owners are notorious for running non-deductible personal expenses through their business for example when they really shouldn't. Plus some super egregious stuff I can't begin to get into here. It is trivially easy and the state/fed gov can't begin to crack down for lack of resources. These are your tradesmen like plumbers and electricians, boutique shop owners, salons, food/catering, smaller self employed professionals like doctors, lawyers, therapists, dentists, etc. It's sort of a grey area and there's wiggle room for sure, and I try not to let my clients get away with all of it. But I do look the other way a lot and just plug my nose and sign it and push it through when I'm in a hurry, which is basically always. Some people are just maniacs though, it's really staggering, idk how they sleep at night. Smaller numbers than a hedge fund manager making $50 mil, but it adds up real quick, and fraud is fraud IMO.