In the UK, the kind of people who visit National Trust properties are the kind of people who carefully read all the signage and actually listen to the tour guide.
"...most definitely it wouldn't work on a general touristic place"? That's a pretty strong statement to use with no proof.
The sites that the National Trust maintains are "general touristic places". It's the UK's largest membership organization, with a membership of 3.7 million people in 2010. It owns over 200 historic houses. It owns more than 630,000 acres, nearly 1.5% of the entire land mass of England, Wales, and Northern Ireland, and owns or protects roughly 20% of the coastline.
One of its properties -- just one, and remember that it owns over 200 houses and 630,000 acres of land -- had nearly 440,000 visitors in its 2009-10 fiscal year.
National Trust properties are most definitely "general touristic places" at which these signs are working.
This idea is delightful.