youths U16 and younger, early development teams explain and go again the first time; subsequent occassions scrum it (never FK !)
I think many referees used to adult rugby have a massive blind spot about this. Of all the complicated Laws and skills required for rugby, somehow the quick tap has become something that referees consider so difficult for young people to understand or master, that they need a on field coaching and second chances.
in england quick taps come into the game at U11 ! I can distinctly remember the first half of the U11 season where switched on teams who thought of taking it quickly took slower-thinking opponents completely by surprise by tapping and running. quick taps were very popular from day one - and still are
when I was reffing u11 it was indeed appropriate to explain and to let them take it again, especially when quick taps were attempted by eager ten-year old forwards who found themselve with the ball and thought they would have a go.
The idea that
five seasons later, referees are still earenstly explaining the concept of quick taps to U16s make me snort with laughter. The reason the SH tapped it on his boot wasn't becasue he didn't know, it was because he hoped you wouldn't notice, or if you did notice you didn't care, or if you did care you'd most likely let him take it again anyway.