They made assumptions, leaps of logic, out of ignorance and decided to act on them in haste
So did the driver. The driver made assumptions that there were no additional connotations for "Lolita" the fashion trend out of ignorance and hung a sign they assumed wasn't disturbing but was for reasons they did not know. If you're just judging people by their actions, the driver's intentions you have detailed should hold as little weight as the parents' intentions. And what the driver did was stupid and caused harm, intentions aside.