I don't think you will find a standard answer. Depends on the company, the team, your experience level, how technical the PM role is, etc...
PM salary could be higher or lower but from I've seen, broadly speaking the roles earn about the same...Sometimes you will see developers base salary higher but then PMs can get larger bonuses.. but meh I would say on average they are going to be very close to the same when you look at total comp, ceteris paribus.
There might be a supply and demand issue in some markets. No offense but 'ensuring people are aligned and the focus is correct' is not very hard, at least not harder than grinding away developing. If there is a shortage of developers vs. the number of roles needing them but there's enough guys who can do the PM-babysitting type roles then in those markets developers earn more.
I know companies that would fall apart in a minute if the administrative assistants and secretaries weren't there on the ball. The company seriously depends on them being good and they get paid the least. Responsibility and impact is subjective.
Anything goes when it comes to higher levels of experience or legit superstar PMs or developers, they will be able to get paid the most. So if you are a talented and experienced developer but not able to be a standout PM, well that's that.