Most bills die at a committee. Committees control when/if bills will be heard. If they approve it, it will be heard by the House and the Senate. There are many steps to pass a bill. I believe it is difficult to pass due to constant disagreements about what is in the bill. There are many other reasons as well. Even if the committee passes a bill, there’s no guarantee that it will go through the House and Senate (as they don’t agree on many things these days).