Tomato Products containing Citric Acid
Citric acid in canned goods is just a preservative, nothing to do with "ripening in the can" as far as I know.

As you've noticed, it's plenty common in storebought canned food, but it's especially useful in homemade canned food. It keeps canned vegetables from darkening/browning over time, and can be used to make them acidic enough to avoid worries about botulism and spoilage. (Other things like ascorbic acid can also be used to keep colors bright.)

If it's really a problem, you may be able to find canned tomatoes without it, most likely more expensive ones from brands that want to be able to have the ingredient label just say "tomatoes", perhaps organic tomatoes. You might also just try different brands even if they do contain citric acid; some of them might be more to your tastes.

But the acidity shouldn't be that strong, so it's quite likely that just a little bit of sugar will cover it up, and as a bonus it'll tend to enhance your perception of the tomato flavor too.

As for spiciness of jarred sauces... well, some are spicy, some aren't. It's just about making flavors to suit all tastes. Pick one you like!