I have notices listings for License Plate Covers on Amazon and other websites. I believe that the purpose of such covers is to prevent the police and other governmental agencies from locating and billing a fine to the owner of a vehicle that has violated a law.
A simple Google search would suffice.
License plate frames can be illegal
New York State Police Set To Crack Down On License Plate Alterations, Covers
Is it legal to sell such covers? Or to operate a website where such covers are offered for sale?
How much money and time do you think the state of NY is going to spend on such a nonpriority of a legal issue as to
How are they going to enforce state law against websites outside the state and even outside the country?
And all the site has to do is...
1. Put up a disclaimer that people shouldn't use the plate covers where the item is illegal to use;
2. Make a claim that this plate cover isn't a plate cover but... say ... a work of art to nail to your living room wall and they can't do anything about the buyers who end up using the item to cover their license plates.
You live in NY state. It's almost guaranteed that you've seen smoke shops sell drug paraphernalia (that would otherwise be illegal to sell - prelegal pot days) but they end up allowed to sell these glass pipes by calling them works of glass art.