> IIRC American companies (specially service companies, but surely also hardware companies) can be forced to introduce backdoors and other spying mechanisms and then force them not to disclose such a thing (i.e. Lavabit, Groklaw, Room 641 and equivalent Google and Facebook programms).

You recall incorrectly. By extension of the First Amendment, US companies are protected from being forced to introduce functionality so as to collect or decrypt information (or for any other purpose). Carrying out original work for the government is considered to be speech, and as a result cannot be compelled. If the data is already collected and available in a decrypted form to the company a court order can compel the data to be turned over as evidence, as is the case with any data (or any thing) held by anyone (with narrow exceptions related to the 5th amendment).

This was a topic of national attention several years ago when the FBI tried (and failed) to compel Apple to create and sign a custom software update to unlock an iPhone.

https://en.m.wikipedia.org/wiki/FBI–Apple_encryption_dispute