The thing is that liberals see most self-identified libertarians as being completely full of shit. At best, they're in the "I've got mine screw you" and "freedom for me but not for thee" crowds, at worst they're complete sociopaths.
But leaving behind the degree of fullofshitness, there is a liberal view of abuse of state power which self-described libertarians often mention but rarely get that passionate about. Much better to fret about high taxes or occupational licensing. Unwarranted mass incarceration, unaccountable police brutality, authorizing the state to kill its own citizens, absurd civil forfeiture procedures... these are all clear abuses of state power! Much of the rest of it is just a debate over what should be appropriate policies, not whether they're abuses (though glibertarians tend to call anything they don't like an abuse of state power).
There are people such as Radley Balko who take this stuff on! Good for them! Liberals would like libertarians more if they spent more time on the militarization of the police and the approved abuse of (especially) minority populations rather than, say, seatbelt laws and top marginal tax rates. Because top marginal tax rates aren't actually a libertarian issue, just a conservative one.