So instead of extending QR codes, which are inherently binary, to efficiently handle binary payloads, we invent yet another ASCII-based tunneling scheme. Why ever fix any problem when we can just pile workaround upon workaround upon workaround?
Because QR code scanners are very widespread already, can be understood by even basic cameras nowadays and some devices are hard to update or would need yet another self-invented thingy, which would make people rather more suspicious if done for something like the use case this initially had – codes for verifying that a person is tested, vaccinated or recovered OK on borders and the like.
I at least find it good that existing solutions still get optimizations, even and are enhanced, vs. just throwing everything away at the slightest issue and redo everything, the that churn just costs a lot of $€£ while never bringing out something mature, i.e., useful for the masses.