Clearances can take time and become burdensome if it's an absolute requirement. When I was in school one of my teachers said his dad's company had to repair air

Clearances can take time and become burdensome if it's an absolute requirement. When I was in school one of my teachers said his dad's company had to repair air conditioning equipment at a special forces training base, and what he described was similar (except this is prior to cellphones, so no electronics destruction). The alternative is costly and time intensive security clearances for every conceivable profession and to share it across the country. It makes sense for janitors and common forms of maintenance, but for less common things this is a viable workaround.