An interest group that appears to have many grassroots members but in fact does not have individual citizens as members is called what?

It is called " AstroTurf "

Explanation:

An advocacy entity political concept that seems that there are many individuals in the grassroots, but does indeed not have individual citizens as members; instead, an entity such as a company or a business association promotes this term.

The method is to mask a text or firm's sponsors (e. g., politics, publicity, religious relations, or public affairs) to appear as if they come from the grassroots and are supported by them.

The AstroTurf company was purchased by SRI. The American Sports Products, Inc. purchased SRI in 1996. Whereas AstroTurf was the market leader in the late 20th generation, in the early 2000s other firms were formed.