The TO-220 packaged VR1 regulator and Q1 transistor in the Commodore 64 motherboard (reference designators cited here from the Rev. B breadbin) are mounted in a way that suggests they were supposed to be tied down to the PCB to thermally couple the metal tab of the package to the PCB.
The legs are bent, there is a significant area of metal from the PCB exposed with no solder mask below the package, and holes are drilled to match the hole in the package's metal tab.
Yet, these components are not mounted onto these areas with thermal paste and screws, just bent over, barely or almost touching the PCB, as seen on the images from assy 250425 below:
Commodore were renowned for their cost reduction measures - is this likely to be an instance of those, having found the cooling to be sufficient without screwing the packages down, or is there a likely engineering reason, e.g. to get more airflow around the packages?