aren't moped expected to just drive on the main road, next to cars, and require a helmet and license plate?

Scooters are "more different".

Dutch law has two classes of 'moped'- both were originally conceived as motor-assisted pedal cycles, but in practice both are now mostly Vespa-type scooters with no option to pedal.

Both require insurance and an 'insurance plate' which is a different format from the standard licence plate seen on motorcycles. The rider must be licensed, but this can be either a car or a motorcycle licence (or a moped-specific licence which can be obtained from the age of 16, compared to 18 for cars and motorcycles).

The 'snorfiets' scooters have blue number plates, and are legally supposed to be limited to 25 km/h. The rider does not need to wear a helmet.

The 'bromfiets' scooters, with yellow number plates, are legally supposed to be limited to 45 km/h, but the rider must wear a helmet.

(In practice most scooters seem to routinely go much faster than they are supposed to be capable of)

In general, both types of scooter can use some, but not all, bike paths. A snorfiets is allowed on more bike paths than a bromfiets is- bromfietsen must ride on the main road in built-up areas.

All I can say is that the reality is that they come right at me on the bike path on the wrong side of the rode at 16+ mph. Every single time I go biking.

Whatever rules exists here exist on paper only.

I can understand. When vehicles of different cruising speeds share a roadway, the faster ones are perpetually passing. So always oncoming straight at you. It gets worse with increasing density - instead of passing occasionally, now you're passing pretty much all the time.

Its a hard problem to solve.