There is a difference between weakened and backdoored. Weakened is along the lines what you're saying - that likely others than just the governments can easily access, whereas backdoored (if done properly) means only the govt. Of course, this assumes a perfect world and that there is a proper way to backdoor - in the real world, adversaries simply attack the governments backdoors/keys.
Nonetheless, given your context of "there is no encryption going on at all" I argue does not necessarily hold for a backdoor - or at least not at the outset and if done properly. If the govt backdoor is a key for which huge amount of care is taken to protect and take the extreme example of the govt encrypting the only copy of the key and firing it off in one direction into space - there is a backdoor but this is not necessarily equivalent to "no encryption at all".
Nonetheless, given your context of "there is no encryption going on at all" I argue does not necessarily hold for a backdoor - or at least not at the outset and if done properly. If the govt backdoor is a key for which huge amount of care is taken to protect and take the extreme example of the govt encrypting the only copy of the key and firing it off in one direction into space - there is a backdoor but this is not necessarily equivalent to "no encryption at all".