Providing a UBI doesn't mean market forces vanish, it would just shift/adjust those market forces. I think these "shit" jobs would either cease to exist if they

Providing a UBI doesn't mean market forces vanish, it would just shift/adjust those market forces. I think these "shit" jobs would either cease to exist if they weren't really necessary, be replaced by automated solutions, or be compensated at a high enough rate that someone would be still be willing to do them. It seems like all three of those would be net positives economically.