Every mistake, every crash is a failure and there are remarkably few of them. Mistakes happen and the mistake is always in not predicting the failure correctly.
And there's quite a bit of competition; Boeing and Airbus are integrators, they don't build all of the parts and there are plenty of parties competing for the various parts. Likewise they both make the largest aircraft exclusively, but as you get smaller you add more and more alternatives to the mix.
You're also wrong about no new models. They release updates and changes all the time. Completely new planforms just aren't needed. The basic design is fundamentally unchanged and doesn't need to be changed. There's just nowhere to go. Only small iterations of improvement.
There are plenty of opportunities for new models; Boeing wanted to make 3 new aircraft, and had to settle for 1 new and 2 upgrades. The 737 has been flying for almost 50 years, and Boeing still can't give it long enough landing gear to properly accommodate properly-sized turbofans because of the regulatory burdens. Bombardier thought there was an opportunity for a new single-aisle airliner, but hasn't been able to come up with the money to get a certificate.
The fact that there are no new aircraft manufacturers coming on-line only proves that the regulators have created a duopoly.
And there's quite a bit of competition; Boeing and Airbus are integrators, they don't build all of the parts and there are plenty of parties competing for the various parts. Likewise they both make the largest aircraft exclusively, but as you get smaller you add more and more alternatives to the mix.
You're also wrong about no new models. They release updates and changes all the time. Completely new planforms just aren't needed. The basic design is fundamentally unchanged and doesn't need to be changed. There's just nowhere to go. Only small iterations of improvement.