With the heavily connected tech world we live in it's going to get harder and harder to evade taxes. I would think the IRS can tap your name into a computer and boom, EVERYTHING is recorded and tracked. Who your contacts are, who you phone/text, where you drive or go on business, real-time data on your bank and brokerage accounts and so on. Run the data through their alogos and if up to no good they'll spit out your death sentence. Some might say 'oh, what about the data laws in force to help protect us'. Hahahaha, if you haven't already noticed the laws of the land aren't a concern for them, even if they break them. What 99% of us don't realise, including me, is just how advanced their tech is. I reckon we'd be shocked if we knew of their capabilities. Same with crime. With all the surveillance, it's not a good move to get into criminality these days. Listen to many of the old gangsters, they all say crime is a one way ticket to jail, so go get a non-crime job.
I think you are overestimating their skills. Sounds like this guy got screwed by his Swiss Bank who handed over the info to IRS (because of new reporting requirements) and it snowballed from there.