Why is that important? There are many reasons. That seed might be treated with chemicals. Could be even GM seed and you won’t know. They will probably have needs to use fungicide and similar things to keep plants healthy because of the number of plants in their greenhouse. More plants, more diseases, pests, and then it is hard to control, which is why all who grow ‘big time’ use many chemicals.
Start growing your plants from seed. Get containers, sterilize them and fill with soil. Here on this photo is my nursery from a few years back . Those are special containers which you can find in every better store where is sold seed, soil etc. First year you can use anything you have. Look around and you will find a number of possible containers. Use plastic yogurt cups, toilet paper rolls, plastic bottles, party cups. Make sure to get seed from your friends or farmers if you know they save their own and not using seed from big companies. Avoid risk of buying GM seed. Make sure to prepare seed for next year from your own vegetables.