Perhaps you could use fusion of cheaper sensors to provide good enough location information. What is lacking though is the software and regulatory framework to

Perhaps you could use fusion of cheaper sensors to provide good enough location information. What is lacking though is the software and regulatory framework to do that. It requires a change in philosophy. In the past you had an ensemble of data that had very good statistical reliability and could be a source of truth. We are moving to systems where individual sources of data lack that reliability due to physical limitations. That is a hard problem to solve. You can see similar issues in aviation.