Except that I don't evade taxes, and I don't want the IRS using my online presence to profile me and decide if I fit the profile of a tax evader.

The IRS doesn't use your online profile to decide if you're a tax evader. It's simply fearmongering from anti-tax advocates.

The IRS doesn't even have the budget to carry out basic audits in which the bulk of the investigational burden is placed on the taxpayer (by means of responding to auto-generated documentation requests). It certainly doesn't have the budget to invest in a high-tech system that could track multiple social media platforms and somehow connect that to financial spending or tax reporting.

Being afraid they might get things wrong is like being afraid your car might lose its wheel on the highway.

Could it happen? Yes. Is it a risk one must take in order to partake in the luxuries of the lifestyle one leads? Yes.

Except it's exactly the same.

It is not. Tax evasion is an actual crime. The IRS using public signals from social media to determine if somebody is cheating on their taxes is not the same as the NSA tracking your GPS location via your cell phone at all times.

"If you don't have something to hide then you shouldn't mind" ... "They do have something to hide, so fuck them!" is two sides of the same coin.

You are correct. Perhaps I did not make my point clear. If you publicly post pictures of your new Porsche and your newly remodeled kitchen and claim that you only made $10k last year, why should that not be cause for the IRS to take a deeper look? You do not, by definition, have any expectation of privacy in that scenario. If you sent the picture of your new ride in a private message, that is a different story.