Originally, RT was more or less a 'good faith' measurement of the general sentiment\quality of a film, but it is so easily manipulated it was inevitable that it would become meaningless.
While they definitely measure on different metrics, the goal of a critic is supposed to be to measure films worth watching (even if only for a subset of the total audience). When 95% of critics tell you to see a movie that only 10% of people enjoy, something's broken.
Well... expectations shift between a movie ticket and a bucket of popcorn for 10€ or the same for 30€.
Cinema has gone really damn expensive, and loaded with ads to boot - but movie critics don't get that crap experience, they get exclusive previews. It's literally a different world.
My GF adds other points: while the audience as a general loves "typical plot" movies, critics who have to see 20 movies based on the same formula a year will be sick of it.
Imagine applying that metric to any other job.
"Fuck, this is the 20th React component I've had to build...I'll just do it shitty instead."