There is very little requirement on equipment to fly in the US, you don't even need a radio in the majority of the space (only when you approach towered airports and other busy / special areas). So we're far from requiring a camera :)

Sure but for what GA costs on a recurring basis, a small camera or two is such a negligible cost and is really valuable for learning.

Not to mention, there's a great possibility that these unidentified aircraft are American.

What you say may be true, but the conclusion isn't, I don't think.

Case in point: the FAA now requires a digital transmitter beacon (ADS-B) in most of the commonly used airspaces in the continental US as of last month.