Libraries and library systems are a major, long-term target of the security services and politicians. Those guys want to know if you read "Steal This Book", or in an older age, "Lady Chatterly's Lover", so they can blackmail you. The library community soon learned that it was smart to meet the most stringent privacy standards set by law. After all, you also can't afford to cheese off Germany and the EU and get tossed out of their market.
Countries who would prefer to have back-doors have a hard time making a case for them, as they don't want be seen publicly trying to convince a company to break a good law.
The same logic applied to all software: China has just encouraged all countries to demand open or at least auditable source, and builds that can be proven to be from those sources, so customers can be sure that the backdoors aren't in.
Smart customers will insists on open source, so they can check themselves.