>Full time work however is NOT allowed without a working permit.

If you're being paid through an account back home and are working in a villa you've rented, it would be very hard for them to prove you're actually there working full time, would it not?

This is not about how hard it is for Thai immigration officers to prove you are working without a permit. I was just pointing out that it is illegal. Making it hard to prove doesn't make it OK.

You really would not want to end up in a debate with Thai immigration on this topic either, no matter if they have proof or not.

Digital nomads are huge benefit to local economy. I can't imagine country would start enforcing some outdated piece of legislation against them. In other words, even if it's illegal, it's not enforceable.

Outdated legislation which is no longer enforced is common everywhere. For example Alabama has a homophobic law which says this must be included in every sex education program:

"homosexuality is not a lifestyle acceptable to the general public and that homosexual conduct is a criminal offense under the laws of the state."

http://codes.lp.findlaw.com/alcode/16/40A/16-40A-2

Illegal != Enforceable

While I have visited the USA several times I can not comment on US law. I have lived several years in Thailand and can guarantee that illegal action by intent like working without a work permit is enforcable. You are trying to apply a Western point of view, digital nomads are not considered to be an economic benefit by Thai law officials.

A Digital nomad paying no income tax, quite likely claiming back the VAT on purchases (because they're ostensibly on tourist visas), and often specifically in the country because its very cheap, are not having a huge effect on the economy.

REAL tourists have a HUGE effect on the economy.

REAL businesses that make the effort to operate legally, employ local staff, pay taxes, etc, have an effect on the economy.

Doesn't make it any more or less legal though.