But how is that any different from the intended recipient losing control their key?

Take a look at the number of people who lose their crypto keys and watch their money vanish.

All encryption is broken by the virtue that key management is impossible for most people.

The intended recipient does not hold a master key to an entire nations communication. That's the difference.

The govt key decrypts everything, real-time and stored/archived, sent in that nation during the time it is in use, and that key is in use in multiple places/machines, and is in an org that is a high-profile target for many other reasons (so could likely be exposed in a crack that initially had other purposes.

In contrast, a person's key can decrypt only that person's messages, is used only in one place (usermset of machines), and is a generally low-value target.

Insanely huge difference between losing a person's key vs the key to an entire nation's communications, even if it is the key of the nation's president -- still far lower value & consequences (start with: if you have the nation's key you can decrypt the president's comms anyway).

One person losing control of their keys only really affects them and people they talk directly to. The government having some super key(s) that access everyones messages affects everyone.