Why don't some Italian tomato sauces and pastes use citric acid?

E330 - commonly named on a labels as citric acid to not scare consumers - is an antioxidant. In tomato sauce I would say it's used to stop it from browning (and as a mild conservative).
The difference beetwen European and North American is just a shelf life of sauce. Both on shelf in store and at home.

Citric acid is added when the PH of the overall product is too high. Most of the time a product with pure tomatoes doesn't need any help with PH as the tomatoes should be acidic enough, when you see citric acid added you will usually see water added as well in some form. Water is added to bulk up the product and make it cheaper, some companies add tomato juice instead of water as it looks better on the labeling , but at the end of the day tomato juice is just flavored water. Water increases the overall PH level, so you have to bring it back up.

When you don't see citric acid in a can of tomatoes or a tomato product it's usually a sign that they are really good quality.

The citric acid in your tomato cans is insurance to cover the cost cutting and arguably lower standards without getting customers sick.

I'm american, but have traveled. Factory conditions in North America are not the same as in Europe. They are dirtier and more "cost efficient". Therefore american companies will take extra measures to ensure safety that traditional European methods and practices naturally provide.

For example, US eggs are laid in (relatively) filthy and overcrowded cages, so they get feces and food bits all over them right away. These eggs must be washed, which removes the natural mucus layer that protects the egg. This means US eggs need refrigerated, while European ones do not. Technically, the US eggs are "cleaner", but the back story is telling.

American tomato puree likely has fruit from the ground, over-ripe fruit, fruit where rotten sections are (hopefully) removed, etc. They then use chemicals and physical processes (microwave, UV, pasteurization, etc) to make sure these potentially dangerous supplies don't result in sickness. Taste suffers, but the costs can be lower.