OS question

Why aren't OSes written in safer languages(e.g. Ada)?

I'll tell you a secret why your AutismOS is unlikely to succeed,
Its because your OS is built to be incompatible with mainstream drivers,standards,apps and games.
If your OS could natively(or almost natively) run windows drivers,games,apps and use all features of windows/max/lunix(i.e. being useful from the start) it will be a success.
But no. AutismOS will only support your own drivers, apps have to be ported and games are for "faggots" who can't appreciate the terminal and VGA pallete.
Just to provide perspective, Early windows was built to be compatible with all aspects of DOS.
Early Lunix was (somewhat)compatible with Minix and supported POSIX/Unix userland,
Only Macs had the luxury of "NIH autism" working since Apple controlled the hardware at the time and even then they were expensive shit for niche audience(hipsters and idiots with cash to spare, as always).