Because it involves various stages and personnel and often does not get a bill passed.
Explanation:
The United States legislature was purposely designed to be slower in taking action. This is because the founding fathers wanted to prevent the infringement of citizens' rights and freedoms.
Thereby, the legislature involves various personnel and stages before bills and laws are passed. Also the legislature is bicameral in nature as it requires the passing of House and Senate through debates and votings.
