This is a follow up to this post. The OP there shared the data they collected. I can't confirm if the data was collected properly, but it looks legit and so I did a bit of independent analysis to add some different visualizations.
This is isolated to CAN vs USA games, and I do PIM per game rather than for the playoffs as a whole to make the trends a bit more stable.
The top graph shows the average PIM per game for Canadian and US teams, along with the absolute per-game difference. The middle graph shows the delta as a percentage of the total PIM per game.
The bottom graph shows the same for Home vs Away.
A few interesting bits. For one, the number of penalties called in the playoffs has been steadily decreasing. Though I can't say if that's different officiating standards or better player discipline (and fewer fights).
Second, since 1993 American teams get 13.0 PIM / game in the playoffs while Canadian teams get 14.0, so an extra minor penalty every other game. Pre-Bettman it was 22.2 for the US and 21.1 for Canadian teams.
Interestingly, the Home V Away trends are almost identical. Home teams get 13.2 PIM /game in the Bettman era vs 14.1 for away teams. And pre-Bettman the results were 22.3 vs 21.0.