Both are right. The older ones with squiggly letters, numbers or that ask you to identify animals or objects were being used to train ai bots.

The ones that ask for crosswalks, bikes, overpass, signs etc are used to train self driving ai.

Magnets are very weird. Up until now, we don’t really know what causes magnetism or how it works. We just know some rocks have it and others don’t. Also, magents aren’t super massively available in nature.

I’d hazzard a guess that guy refers to magnets the same way we SHOULD treat helium. It’s a precious rare non renewable resource and we squander it like it’s nothing.