After 5 pm the police are asleep or ...

100% helmet use campaign started in Phuket last November.
The following month a nationwide campaign was kicked off.
Quite recently, posters and banners started to appear locally promoting the campaign.

The campaign seems to be working to some extend, but it's not quite 100% yet.

While adults wear helmets, their passenger children are mostly without head protection.

5 pm seems to be the time when helmets are discarded by almost everyone.
As one neighbor explained it to me, after 5 pm the police are asleep or...

I'd suggest eventually the law will expand, requiring eye protection for motorcyclists.  It's mandatory in many western countries.  Until then, we'll see plenty of eye patches.

Somewhat reminds me of the headlight law.  When I first started driving a motorcycle in Thailand (2003), Thai's would laugh at me for keeping my headlights on during the daytime.  A few months later it became law.  But it took another year before it became accepted practice.

Motorcycles sold these days are manufactured in a way that the headlights are on automatically when the engine is running.  Unfortunately helmet wearing can not be built into motorcycles.