Yes, because businesses struggling for cash invest in support for people who aren't paying them...
Google gets away with the quality level of their services because they are the information discovery monopolist.
I think those two services are incredibly strong products and gmail is additionally a positive equalizing force, allowing much closer to everyone to participate in modern communications.
It’s maybe technically true that these problems would disappear if maps had to feed itself, but I think that would be a net negative for the world.
Hard to say for Maps. There were maps freely available before Google Maps, but they didn't look as nice and they didn't have Streetview and the routing services, and you couldn't embed them on your Website for free (well, paying with you visitor's data, really).
For Gmail? I feel like emails were more reliable before Google decided that any email is likely Spam unless it's sent by one of a dozen commercial providers. Gmail didn't jump ahead in features like GMaps did vs the existing systems, it had a nice web interface and came with a lot of free space in exchange for reading your emails to create a better profile for targeted ads, but that was pretty much it.
I used to have no spam filtering at all on my mail (other than human visual grep). That was ok through 2003 and barely tenable up until about 2007. I then tried to run my own with SpamAssassin and the like. Around 2012 I folded and switched to running inbound mail through gmail. Life immediately got massively better. I almost never see spam and my own domain mail (outbound self-hosted, no commercial provider) gets through to gmail users just fine.
Yes, I get some false positives (ham categorized as spam). I probably have undetected false positives as well. It’s still 100% worth it as email was getting difficult to use previously.
Google false positives on the other hand are a pain in the butt. Even sending from one GSuite account to another on the same domain does not ensure delivery (but makes it much more likely than using a dedicated server that has low traffic to Gmail). I've adapted and now use my own Gmail account if I need to send email to Gmail users that is somewhat important.
Yes, because "free" collapses that entire market and makes it hard to ever get anything else, all while granting a massive amount of power to a company that is happy to break the ecosystem. GMail 1. makes it hard for any new email companies to get off the ground by making it hard to get income, while 2. making it hard for anyone (not an established major player) to successfully send email without it getting blackholed. That is, I blame GMail for the fact that I can't spin up my own mail server and send email and have people actually get it.
Perhaps put better: GMail and Google Maps did improve on what was then available, but in a way that also makes them dead ends for the entire industry, unable to improve beyond a certain point because of how they work while at the same time preventing anyone else from being able to make something better.
This wouldn't matter if Google weren't a de facto monopoly.
If Google were forced to spin Maps out such that it had to stand alone or die rather than being subsidized by the Eye of Sauron, these problems would begin disappearing.