Are there cultural or ethical differences from country to country of tolerance for human trafficking?
There certainly are differences in how serious various cultures think human trafficking is. Of course, these attitudes can change over time. A good example of this is how slavery was seen as normal in the US less than 200 years ago and is now unthinkable. So just because a country's culture accepts human trafficking now does not mean that it always will.
In general, countries where people are very poor seem to accept human trafficking much more than other countries do. Perhaps the best known example of this is Thailand. Thailand is infamous as a place where people from rich countries go as "sex tourists." They go to the many brothels there, including many that have children as sex workers. The workers are trafficked from countries all around Thailand. The people of these countries obviously have a culture and set of ethics that finds this more acceptable than we in the US do. (Of course, there is prostitution and even child prostitution in the US. However, if it were as open and prevalent here as it is in Thailand, it would never be tolerated because our culture feels more strongly about this.)
This is not to say that we in the US are morally superior. It may just be that we are richer and don't have to allow this kind of thing. One way or the other, however, it is clear that some countries are more tolerant of human trafficking than others.