Because they are cowards and taking innocent gay barbers, sheet metal workers that are family men, and teenage barely men is easier than facing a tatted up legit MS13 gang member who fires back and fights back.
I don't think it's just the quotas. My past experience with CBP and specifically things I witnessed at border crossings led me to the conclusion that the very nature of the job attracts people who basically have a sadistic streak and enjoy having that kind of power over others and exercising it.
Imposing their will isn't waste as far as the administration is concerned. All acts, right or wrong can be spun as them doing something.
And the current administration doesn't care about "waste", they only care if the given policy, department, money advances their goals / corruption and etc. They're happy to waste in that context.