I'd love to know where in Europe you are because you certainly aren't in the UK. I can only think of a few test sites that have fibre to the home here. Anyway that's beside the point. Where the cables get put is probably more to do with tradition than anything. In Europe it's traditional to put them underground so we don't have many poles. If you want to lay a new cable you have basically no option but to put it under ground.
There are plenty of problems with underground cabling though (at least in the UK). Up until fairly recently very poor records were kept about where cables were laid under ground. The utility company might know the cable ran along a particular road and maybe even which side but little more detail was kept. Each company laying cables also used to work completely on it's own installing conduit that was much larger than needed for future proofing. Then there's the upgrade problem, I live along a busy main road that has been in this spot for 200+ years, in the pavement outside our house there are at least three different gas installations and two, maybe three, different water installations of varying ages. Only one of each actually works but it can be really hard to tell which because one muddy pipe looks much like any other and other works have to avoid all of them. Combine that with sewer pipes, electricity, phone and cable and you end up with a right mess. If you are wondering how I know it's a mess we had to get the street dug up when we moved here to have gas fitted, the gas fitting guys hit the electrical cable and took out the power for about 1000 homes - Doh!