Right, but... we violate that all the time. If I'm abiding by the other terms of the tourist visa (90/180 days, e.g.), and all the work that I do is for a company in my home country, paid by that company in my home country bank account, and occupies about an hour a day max, I don't think it violates the spirit of the law (the letter of the law is, of course, subject to judicial interpretation).

Is it a violation of my tourist visa to take a phone call from work when I'm on vacation?

The big benefit is the prolonged duration of the visa that allows you to really settle in and live there for a while.

If you're at customs and asked what your plans in the country are, you should not say "work", unless you are authorized to work in the country.