Sadly Prestel just never had the penetration of Minitel. As an Englishman who came-of-age in the 1980's I wasn't aware of anyone with Prestel, it was too expensive. I remember my dad, who was pretty keen on technology (we had a sonic remote control for our TV I'll have you know) saying that they needed to make it's use free, even if you have to rent the kit. Charging for calls meant you had to think before you did and in the early 80's had any idea what you would do with it. They needed to be allowed to play for free first.