The tomatoes you find in a shop have been picked before they are ripe so that they ripen during transport. This improves yields and reduces spoilage and bruisin

The tomatoes you find in a shop have been picked before they are ripe so that they ripen during transport. This improves yields and reduces spoilage and bruising. However, it results in a tomato that - while it looks like a normal tomato - the sugars and other flavours don't develop in the same way, rendering it bland. If you want to buy tomatoes that taste good, you can get them from a farmers market and they will taste a lot better - even if grown in the same soil with the same techniques as the supermarket tomatoes. Alternatively canned/frozen/preserved tomatoes tend to be made with naturally ripened tomatoes. Obviously you can't really used those tomatoes the same way you'd use a raw tomato, though. This isn't specific to tomatoes, many commercial fruits and veggies are picked before they're ripe.