Answer: Grants require match for many reasons. The main reason being, the funding agency wants to see the applicant is also trying to provide for the program and not fully dependent on the grant funds. Additionally, grants require a match to ensure the program can continue once the funds have exhausted. Many funding agencies look to fund programs that are worth funding.
Funding agencies like to know that there are other parties interested in seeing your program succeed. They want to see they are not taking on the full burden of a new program. They look to verify the program is an interest to others in the community.