That is more mediocre versus bad. Most of the bad transit systems I'm aware of don't have service to large events at all and so it's not an option.

Fair point. I likely never encountered truly bad public transit since it was never pointed to as viable.

There are a lot of unviable transit in the US. Most transit systems have large unviable parts even if there is a viable core (generally in the city center). People often blame the unviable on lack of density, but there are examples of viable transit systems elsewhere in the world that have US suburb density.

Can you share some examples of viable transit systems in areas with similar density to US suburbs? I'd like to know more.

Nothing specific, but when you look at European cities you discover many of them have areas with similar density to a US suburb and yet have good service.

I do browse on Google Maps from time to time, and I do see areas with similar-ish density. I also see a lot of cars. I've known a few people who have lived in such places, and they say their transit is near useless (poor service intervals, limited hours, doesn't go everywhere, etc) and most people drive if they can. Which will be less than in the US, as operating a car is often considerably more expensive there than here, tipping the math towards just accepting the poor transit service.

Which is why I was curious about specific experiences.

And I do say, better than many US suburbs which have absolutely no service at all.