Blinks had to let it slide at the time for fear that Blackpink would get an even worse dragging if the truth was known outside the fandom, but they didn't cancel the second Fort Worth date because of low ticket sales. They cancelled because somewhere along the line someone or several someones were incompetent enough (YG things) to schedule a concert at the same time as Jisoo's brothers wedding. They did the first date, then immediately flew back to Korea to attend the wedding.
Even aside from that, their so-called "didn't sell out flop tour" became the highest grossing kpop girl group tour of all time, which says what for everyone else's faves? And yes it's been beaten since. And Blackpink will break the record again.
Clearly a flop tour indeed