Yes. Congressional salaries are not a matter of appropriated funds. The obligation to pay Congress is a matter of constitutional dimension. Their salary comes from holding the office, as opposed to hours worked or particular job done. A U.S. Representative is his own boss, in a sense: if he wishes to stay in his office watching porn for two years, no one (except two-thirds of the rest of the House) can remove him from office for doing so.
U.S. Park Police are paid with appropriated funds, and there’s currently a lapse in appropriations. Even excepted employees, who continue to work, don’t get paid until the appropriations resume – although the government does incur an obligation to pay them.
So it makes perfect sense.
Your plaintive cry arises from some sort of sense of justice.
Guess what, cowboy? Ain’t no justice hereabouts.