Politicians are concerned primarily with getting re-elected. Too many of them just blow with the wind. They are responding to a loud minority of the population who are exploiting a tragedy to advance their political aims.
Increasing the age, more background checks, outlawing bump stocks, etc. will have little effect on shootings. Criminals, by definition, do not worry about complying with such things. The city of Chicago has very restrictive gun laws yet it still have a high rate of shootings.
Who is responsible for the most recent shooting? Not the NRA. It is the shooter himself. The various law enforcement agencies who had the chance to do something about the shooter, but didn't, also bear some responsibility. Why aren't we hearing anything more about the Sheriff of Broward County and the failures of his department? Could it be that he is a prominent Democrat, as are most of the main stream media in the US?
A guy running for sheriff in a county in North Carolina made a "joke" the other day about being willing to kill people in order to confiscate their guns. That is where we are headed if the left gets its way.