Id wager that the biggest issue is just woodworking as a hobby seems less common in most European countries, from what ive heard at any rate. Here in the States its not uncommon to have a house with a 2 car garage or a big shed in the backyard, so having a workshop is a pretty easy thing to do. From the slim bit that i know thats not as common of a thing to have across the pond, so id wager that has a lot to do with the used market being slim. Same reasons that you probably wont find a lot of used table saws in Manhattan.
The only other reason i can think of is that is a lot of the European Union countries have a lot more regulations on safety than the US does, which shrinks the market and drives the price up, which kills the used market pretty effectively. After all here in the US i can buy a pretty bloody good saw for $600 at my local home improvement store, a quick google search of what i might get in Britain show me nothing but jobsite saws, all for a higher price. Personally i wouldnt be woodworking if i had to deal with tool prices that high, and im willing to wager that a lot of people are of the same mind.
Again, this is all just my guesses and impressions