Yes, they also cater to a rather posh clientele. Selling profitably on a common consumer market would likely be a financial challenge. The feasibility of growing these fruits in a Winter greenhouse setting must weigh heating costs in the Northeast vs transportation costs from a more climatically adapted area.
The agricultural area in which I live is in the process of an explosion of high tunnel construction. I'm not aware of any Citrus being grown, however. Common crops are, bedding plants, greens, strawberries, peppers, tomatoes, flowers, and vegetable plant plugs. Although not on the elite level of the Netherlands and Israel, almost every small farm has anywhere from one to a dozen cold frames, mostly toward the lower figure.