If N American refs don't call a lot of fouls, or they interpret the rules in a different way, it's obvious that the players will adapt their play to this style of reffing.
Looking at football, even though most top European league games are now televised across the continent, there is still a significant difference in the level of contact which is typically permitted in English Prem League games than in, say, French Ligue 1 games. Players that have come across from Ligue 1 or Serie A (in which permitted contact is significantly less than Prem League) adapt to Prem League 'standards', and are often found to be enthusiastically adopting the Prem League attitudes to permitted contact.
+1