Don't blame the lack of police enforcement alone for people blocking cycling lanes. It'd be nice to see these people ticketed, but that is NOT the fundamental problem.
It shouldn't be possible for cars to block cycle lanes. They should be physically separated by at MINIMUM a curb. A car should not generally be able to enter the space.
Road engineering affects behavior. The idea that we can engineer to cause bad behavior and then rely on the police to fix the bad behavior is dumb.