At the time 40 bits was not considered a backdoor, it was considered a weakness that would allow folks like NSA (with big budgets and intercept capabilities) to wiretap the way they had other communication approaches.

Some situations, rather than designing new codecs, they would just weaken key gen side. The IBM effort there was public to allow for easier export, but also an approach that could be used to hide the weakness which in other settings may have been beneficial. It's possible however that folks involved understood what was going on to a degree but that it was seen as necessary to avoid export / import restrictions.

More recently I think places like China ask that the holders of key material be located in country and make the full keys available or accessible to their security services. Not sure how AWS squares that circle unless they outsource their data centers in China to a third party that can then expose the keys for China to use.