"You have any evidence for this claim? Any internet access provider can definitely make it much harder for it's users to make use of Tor."
That is true superficially, see http://en.flossmanuals.net/bypassing-censorship/ch029_tor-the-onion-router/
"Tor is vulnerable to blocking. Most Tor nodes are listed in a public directory, so it is easy for network operators to access the list and add the IP addresses of nodes to a filter"
What they don't mention is that as long as a provider allows any sort of general network access, the Tor developers and maintainers will always win. The main circumvention of blocking is hidden bridges. There is also a lot of legitimate effort to detect the hidden bridges. But generally the academic work and best scientific progress comes on the anti-censorship side. Here is just one example: http://www.diva-portal.org/smash/get/diva2:647978/FULLTEXT01.pdf
The most basic tradeoff is "looking like something" to foil encryption detectors and "looking like nothing" to foil bridge connection detection. There are, unfortunately, no alternatives to those two, but between the two there is enough capability that providers have to cripple their network to prevent Tor use.
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.