I'm curious about the "garbage collected" theory as there doesn't seem like a lot of selection pressure to remove tails simply due to them not being useful and consuming energy to grow. The appendix is a far more likely candidate for garbage collection as it has no obvious function and can easily cause death if it bursts.

I suspect that there's another reason that apes lost their tails - most likely related to walking on two feet.

Edit: According to this study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6417348/), the tailed chap had difficulty/pain when sitting and during other activites