I'm really sorry for your loss, but please try to keep a healthy balance between personal tragedy versus medical policy set for a whole population, which are two entirely different things.

For any particular individual, especially those who end up dying from cancer early detection would have likely mattered. Which is exactly where the problem lies: that is a large number of people, but still (much) smaller than the number of people who will end up with positive cancer test. And policy is set by the outcome for the population as a whole, not for any particular individual.

In most places in the developed world cancer screening is already elective, but not for all types of cancer. Even so, how often are you going to do it? Once every year could easily be too slow to make a difference, and these tests aren't free so say a bi-annual test on all of the population would wreck the ability of the medical world to do much else. This is a tough problem to solve, especially because wetware tends to be finicky to work on and tiny little details will have a huge effect on outcome.