Earlier quoted context omitted.
Of course the US considers it illegal. But if you’re a Bulgarian executive running the Bulgarian subsidiary of a US company, they may do things closer to local custom despite US corporate directives. You’re demanding that foreigners extirpate their foreignness while they are employees of a US company. It’s not going to happen 100%.
By enforcing anti corruption on the parent company in the US, the parent company should in turn communicate and enforce their own anti corruption stance and policies on their foreign subsidiaries or branches. If there is no consequence for the parent company then the opposite might happen: extra money used for bribes is provided to the foreign subsidiaries with a wink; now the corruption is increasing.
Now you’re asking a local executive to paddle up river while their competitors go down river.
Unless you have a somewhat leveled playing field it’ll be an uphill battle.
I believe there were espionage scandals in Europe by US intelligence where US companies were given confidential info on other negotiations —this was ab attempt to level the field in the face of what the US saw as unfair competition brought on by bribery.