I disagree. As JDH pointed out, it takes 100+ lines to really be good at them.
It's not just about memorizing the anatomical landmarks and basic steps to the procedure, it's about troubleshooting, and knowing when you're in trouble.
The IJ is a safer line, but the subclavian tends to be easier for the nursing staff to take care of, and has a lower infection rate....so really it's a balance of risks, and the proceduralist should be able to do both effectively....and know when to give up on one approach and try another.
For students, I used to occasionally let a strong MS3 place a line with a bunch of coaching, but not very often. I would routinely let MS4s place lines.
As for non-surgery residents, the volume is typically not there, so they're less likely to let students do much. Also, it's sort of the blind leading the blind.