Not sure how common this us in the US, but where i'm from a wintercheck at the dealer is generally free. Ok mine did ask people to donate €2 for charity, but did gave us as singing snowman... They check of fluids, batteries, tires, AC, wipers, etc. I can do most my self, but I don't have a proper battery tester and having somebody is check is far lazier.

You can use a multimeter to check of parasitic drain rather easily. Battery status and alternator status not so much. I mean yes, you can meassure the current and if the alternator is producing something. But not if it is on the way out but not that good anymore.

I'm happy to life in a moderate climate. I only replaced one battery in a car in my life. Preventive replacement as it was 12 years old, never did let me down and always started.