That's not hard figures. That's relative figures.
Except I literally answered your question
"See Apple jobs listings." That is one source. The fact that they have a Maps team and a separate MapKit team to support Maps suggests it costs far more than maintaining a single app (along with what I said below). I would know because I applied for both teams and got an on campus interview with both. Stop accusing me of deflecting when I literally answered your question.
Nope.
Also, checking their schedule for image collection alone suggests more employees are needed than Garageband
https://maps.apple.com/imagecollection/locations/ (check all the countries that have overlapping schedules) and dedicated team needed to support user submissions of erroneous data. Then they have a backend service to serve billions of requests per day (the fact that high volume third party apps can use this for free like Facebook/Yelp) while Keynote/Numbers/Garageband/Pages/iMovie don't even have a backend service at this scale suggests there's a lot more $$$ involved in maintaining Maps.
You are absolutely in error here. I've provided more than one source and answered your question. Now please address my other points in response to your other statements.