[nocman]

"Nearly every worker in the US is covered by an employment agreement that says they have to get pre-approval for moonlighting."

This is not true.

I've can think of one employer my entire career that had conditions regarding work outside of my normal work hours.

Granted, if you worked for your competetors and they found out about it you could be fired due to trade secrets or conflicts of interest. I only remember one employer I had where I signed something with binding agreements related to other work (and, as it happens, that was perhaps the worst employer I ever had).

I know some employers in some regions do this, but it is a far cry from affecting "nearly every worker in the US". In fact, I am not aware of any of my friends in tech positions currently being under such an agreement (that is, an agreement requiring pre-approval for outside work). In fact I believe it is illegal under many circumstances in some states for an employer to require it (but don't rely on me for that, conditions/laws change, and I have had no reason to look into it recently). I do remember discussions about it in the not too distant past, however.

[jldugger]

It was definitely part of the agreement when I worked in Univerisity IT, and part of the agreement when I accepted an offer from a FAANG company.

The language you're looking for in the contract is 'preponderance of time'.

[piva00]

I don't know about the US but anecdotally it's been definitely the case for most of my work contracts in Brazil and Sweden for the past 17 years, I believe that only 2-3 startups I worked for didn't have a clause about moonlighting requiring pre-approval from management.