Why do the house appropriations committee & the senate appropriations committee, respectively, utilize 'earmarks' more than other committees.?

The house Appropriations Committee and the Senate Appropriations committee seem to be the committees to utilize earmarks the most, as they are the ones to big agencies and funding for government contracts. And not only do these committees fund for those things, the agencies and special interests groups that get the money are linked to some of the most important things in America, including health professionals, banks, defense contractors, and oil and gas companies. Basically, these appropriations committees have the power over the finances of the US.