Zokusho: Speed Demon–Page 35 by Paul on October 7, 2016 at 2:46 am Chapter: Comic Phone booths are totally a thing in Zokusho; shut up.
Where else would the superheroes change into their costume? Its important to have phone booths if you want a save city and they are handy to if you want to hide a time machine.
It could have been a roaming phone booth with higher charges. Normally there’s never a phone booth when you need one then three turn up at once.