True, PVC can be durable, but it has to be the really thick stuff, which is very expensive, often the same price as buying a rail of the same length.
It is also true that a lot of places have started using PVC pipes here in Europe, but they are purpose built ones, and therefore extremely durable.
Fact of the matter is that most of the pictured pipes in the OP would not survive the winter if they were put up in a averagely busy park. Strengthening them with wood could be a solution, but it takes a lot of work, and if the pipe is long or has a large diameter, they can be very heavy and unhandy.