Depends on what you buy and where you buy.
The taste of vegetables and fruit has a lot to do with the substrate in which it is grown. Good soil = good taste. Very simple equation. It also depends on how it's grown, whether it is stored, or if it's in season.
If you like fruit and veg that is not in season, then it is likely to be imported, and as PP have stated therefore old and lost flavour and nutrients, or grown underglass in controlled enviroments, or hydroponically. Even if it's grown here or in the big market gardens on the continent it could be hydroponically grown so no flavour from the soil, or has a lot of water to plump it up quickly, again less flavour from soils.
Some root veg and tuber veg are stored and we are coming to the end of last years produce now, we used to call them Oss Carrots and Pig Potatoes because that's what they were good for, again not in season.
If you buy inseason produce you get a better shot of it being tasty, fresh and fairly local.
Grow it yourself and it's super fresh and tastes entirely different.
In two generations we've gone away from the individuals who cared about the product, sourced locally or from local wholesale markets straight off the ships. Now we have food from supermarkets who are more interested in getting in very uniform, super clean, and plump looking vegetables that fit neatly in boxes that fit neatly in trucks to maximise profit. If it's packaged it's processed quickly but still not fresh when you get it.
Meanwhile perfectly decent local veg gets ploughed back into the soil because the wholesale buyers either don't want to sell because it looks a bit different or to keep prices high for their shoppers by reducing the amount of available produce.
That's why it's worth going to the small independants and markets and paying more for your food if taste is important to you.