Whenever I'm driving I see a lot of highway patrol cars pulled over on the side of the road at these little air conditioned offices where they're likely playing cards, so what you're saying is utterly false. They have enough cars to patrol, they just don't have any motivation.
No, it is not "utterly false"; available highway patrol cars are frequently seen patrolling the highways.
Specifically what is "a lot" of highway patrol cars that you see at those offices - are there perhaps one or two that may be there for official reasons (shift changes, reports, administrative reasons, etc. ?) or even there because the stations' officers will not provide their own fuel for police patrol vehicles?