A relative of mine used to sell memberships to a lobby group that represents small-medium size business owners. A board of elected members would weigh the most trending complaints of business owners, hire consultants to suggest opportunities or solutions, and determine which needed government cooperation. Some of the money is used to literally buy access to a politician. It's typically treated as a campaign donation. In return, you get facetime with the politician. He may, or may not, ultimately support your cause. But let's not kid ourselves, politicians are mostly former lawyers. They don't let their personal beliefs interfere with those of their paying clients. They are for hire.
Funds are also used for PR and media campaigns. And a great amount is spent on the administrative costs. That's right, lobbying itself is an industry, not an inspiring example of civil participation.