That's also true inside Japan. True wasabi is really hard to grow commercially and thus very expensive.

But the source of the spiciness is the same, at least: https://en.wikipedia.org/wiki/Allyl_isothiocyanate

> 95% of the time the stuff with your sushi isn't wasabi

so unexpected that i had to look it up; turns out you're right: https://chefcoca.com/blogs/food-service-equipment-resources/...