So, do you usually write down a paper wallet including the private key and the QR ?
Seems to be quite a lot of work.
Printing can under some circumstances leave traces, that's true.
Old print jobs might be accessible long time after the print job is done.
That's why it is recommended to print from a live booted USB distro and to use a non-network printer with storage for print jobs.
You can use a printer without leaving traces, but a few extra steps have to be made.
No, we can write the private key but not the QR code.
Printing without leaving any traces can be done. This would be safer! As you said, an extra step needs to be taken care and they should know the steps to remove the traces.