And perhaps countries do it because it benefits them that random companies can come and incorporate themselves in their country, but it doesn't benefit them (and often hurts them) when random people can?

After all, there ARE countries where more or less anyone can relatively easily become a citizen, it's just that most people don't want to actually live in those countries.

Some countries give people easy visas on arrival. Others make you jump through several hoops. Why? Perhaps this works out best for both groups of countries. The first group benefits from the tourism dollars, the second group perhaps sees benefits from not having the country flooded by tourists who might or might not leave easily.