Hi @ANTONIOPS
Well, that is how Addons work and you have agreed to follow their rules. Would you prefer is usually not the same as what PrestaShop prefers.
You know that Prestashop takes a cut from every sale, so if you priced them 10 EUR what would be left for them
In terms and conditions, it is all explained how much is their cut and what minimal they can take. But also take into consideration of bank and PayPal fees, then pre-sale support, then preparing documentation, screenshots, marketing, validations...and how much actually is left for you after single sale.
You can try your approach on your own website where you control everything, I did see several developers do something like that. But it is hard to compete with Addons.