Trampoline invasion

On a train journey from central London out to one of the leafy shires this morning, I noticed the proliferation of trampolines in people's gardens. we are being invaded...some without protective nets around them, some with protection, some placed into a hole in the garden and some of the most extravagant and ostentatious designs I have ever seen. If the UK has such an obesity problem with children, why dont we get them to go and live with the evident mulitiude of families who fork out large sums of money for garden trampolines?