There is little if any authority. As one "best practice" can be verboten to some other team, one company's "senior" engineer is another company's mid-level developer. A legendary developer at one company is another hiring team's "bro, do you even fizzbuzz?" It's not that there's no utility at all to using designations, since at the day we are only left with choices to make, but so much of this shit's made up that it's difficult to take anything seriously beyond the immediate task at hand.
I'm glad to be a software developer, and feel fortunate, but sometimes I envy other careers where the chain of command means more. Sure, other industries have their own subjectivity, nepotism, ass-kissing, and so forth, yet for some reason their titles and practices seem to have a legitimacy that lacks in software. Having had my share of ridiculous interviews, I find it gloomy how much an individual's career progression is determined by mere opinion; actual experience is virtually irrelevant. It doesn't even matter if you've written a framework used by big tech to power sites with millions of active users; I know of one of these cases where they were rejected by one of said big tech companies because they "couldn't code."
So although I feel some consolation having achieved the senior role, it's a participation trophy and a "you're a tolerable coworker" trophy wrapped up in one.
It would be nice if the software industry had some form of greater authority to "calibrate" our individual careers. Even companies like The Google have failed to be such an authority.
And no, I'm not suggesting that things were ever different.