Um, their Olympic team qualified for the Olympics, which the US hasn't done for... how many Olympics in a row? And when was the last time Canada qualified? Plus, the under-17 team were U-17 World Cup finalists in 2019. In fact, I think Mexico has a more promising newer generation than the US or Canada.
I wouldn't really take anything from the abomination that was the US Olympic qualifying. Between a horrific head coach selection (lifetime failure Jason Kreis) and a roster construction that was insane (similar to gold cup roster there were no wingers and one attacking midfielder) the team never had a chance anyways, but the biggest reason is that of the top 25 eligible players (my list, so I am sure I missed/overrated players) only 2 were on the team (bolded below) and Ochoa might have been the best US player.
I am not saying Mexico has no good young players, but the current crop of U23's is not on the same level as the US. This cold change as new players emerge, but in my view this is the current state. At the senior level you can see that the previous generation (current 25-29 year olds) is waaaaaay in Mexico's favor. That is the missing US generation.
Christian Pulisic, W, Chelsea
Tyler Adams, MF, RB Leipzig
Giovanni Reyna, MF/W, Borussia Dortmund
Sergino Dest, RB/LB, Barcelona
Weston McKennie, MF, Juventus
Josh Sargent, FW, Werder Bremen
Timothy Weah, FW, Lille
Chris Richards, CB/RB, Bayern Munich
Yunus Musah, MF, Valencia
Konrad de la Fuente, FW/W, Barcelona
Antonee Robinson, LB, Fulham
Brenden Aaronson, MF, Philadelphia Union
Paxton Pomykal, MF, FC Dallas
Reggie Cannon, RB, Boavista
Richard Ledezma, MF, PSV Eindhoven
Sebastian Soto, FW, Norwich
Nicholas Gioacchini, FW, Caen
James Sands, MF, NYCFC
Miles Robinson, DF, Atlanta United FC
Mark McKenzie, DF, Philadelphia Union
Gianluca Busio, MF, Sporting Kansas City
Caden Clark, MF, New York Red Bulls
Bryan Reynolds, RB, Roma
Justin Che, CB/RB. FC Dallas
David Ochoa, GK, RSL