As you noted, it is probably primarily a function of the cultivars the commercial greenhouses are using, likely chosen for their ability to withstand shipping and handling well with less bruising, spoilage, etc. Growing conditions can indeed also contribute to fruit flavor and quality, and the stresses of growing outdoors in conditions of weather fluctuations and pest and pathogen attacks could influence flavor. (While supplemental lighting that might be used in greenhouses can be bright, it's still not the intensity of natural sunlight, which would also probably be reduced a bit by the glass roof and any shade cloth the grower might be using to help keep manage temperature. As another environmental factor, the growing media (potting mix) that is used may also play a role.

Miri