There is one (or two?) underwear vendor machine... in a sex shop. Someone was comparing this myth to the idea that in the US you can have your car washed with stripper boobs, which I am sure you can... somewhere...
The loli genre is frowned upon, but there is a slightly different view of pedophilia here: instead of being seen as psychopaths like in the west, they see them more as immature men-child stuck on highschool fantasies. And let's be frank: Japan is far behind when it comes to fight the rape culture.
'They' in your last sentence is a subset of the otaku culture, what you would now call incels in the west. It is creepy as hell, but it is a fringe minority.