Someone recently described the Republicans and the Democrats in Congress as the pets of the Corporatocracy. They said the Republicans were the dogs and the Democrats were the cats.
The dogs did tricks on command, would slavishly follow their masters everywhere, and would even die to protect their masters. The cats pretended to be aloof and ignore their masters, but still always came running when they heard the can opener.
That about sums it up.
Bernie Sanders, however, seems to be the exception.