Yes, it is amazing to me as well that people sign up for mello roos. I would never buy into a place with mello roos. HOAs are also a huge negative for me but I can live with those. Mello-roos are just out of the question. It truly boggles my mind that people willingly sign up for it.
I’m pretty sure my HOA + tax + mortgage is cheaper than many 4S HOA + tax + mello roos. Luckily I bought my place in 1998 before the run-up.