I ended up installing Big Launcher[1] as an alternative android launcher and configured it so it has buttons to ring three people. That's it. Even then, then confirmation yes/no dialogue when she presses "End Call" gave her a lot of anxiety initially.
I recently had to setup access to a local streaming service on my step-dad's TV recently. The amount of hoops necessary, including installing their stupid app on a phone, and entering passwords for several different accounts, several times, was absolutely ridiculous. Being technologically adept I found it an absolute PITA. It was a complete non-starter for him.
My point is that your, "If he can afford a season pass, he can afford a smartphone," comment comes across almost as callow as the attitude of the Dodger Stadium management towards the very real issues of getting old in a world that is moving faster and faster technologically.
[1] https://play.google.com/store/apps/details?id=name.kunes.and...