I would testify in court that this is not true.
I have had this happen to me plenty of times, especially at a certain drive through with two converging lanes.
But yes, in stores and in person too. Plenty of times. And I was generally less annoyed with the cutter and more annoyed with the clueless clerks who pay no attention to who is next.....yet keep pestering me for a store card and asking if I want a bag.
I have had people ask though too...and this was refreshing. And I have been the asker, especially at ATMs, cause when I just need cash, I will be out in 30 seconds compared to their 10 minutes of transfers. In fact, some have been nice enough to stop part way and go back to the end of the line with no one asking. Japan deserves credit, but Japan is not perfect.
As a principle, I don't go into an argument on the internet

.
However, driving is an entirely different thing. There are no queues where people must wait for their number to come.
But, as far as driving is concerned, I do not rate Japanese drivers in the top position for manners - this is more so for many Japanese with smaller cars. My vote here goes to Germans, after driving on three continents and doing it the most in Germany and Switzerland. Now I am settled in Japan for life (remaining), but yes, you need to be fair.
In stores and ATMs, well, in my close to two decades in Japan (overall), I have never experienced any Japanese jumping the queue.
A very interesting example (not directly relevant - but VERY relevant).
Between 8:00 am to 10:00 am (peak morning hours), get off at Nihombashi station (Tozai-sen), and go for changing to Ginza-sen to go towards Shimbashi station.
A very narrow staircase - with the usual partition to go up or down. Unfortunately, people designed that partition's width according to the horrible evening traffic. However, we can get a peek into the Japanese ways. You will find almost no one coming down in the wide partition. And a huge crowd of people going up in the other narrow partition. Just following the rules.
Well, most of the time, I am the only one breaking that protocol - especially since COVID hit. But, if I really think about it, when one person breaks a protocol, a chain reaction is bound to follow - and the end result is that the rules and protocols get f**ked up.