I understand that it doesn't make the system look better to a low-information buyer. So Lenovo aren't doing it. But Apply seem motivated to add small costs in exchange for moderate (if invisible) benefits.
The problem is rarely poor application of paste, but degradation of the paste's performance over time. The paste can chemically degrade, or it can be pumped out of the interface by the movement caused by repeated thermal cycles. Many manufacturers use a solid thermal interface material rather than a paste, which has poorer initial performance but more consistent performance over time.
I would disagree - to give an electronics example, this level of work is done all the time at large scale on PCB manufacturers with solder mask, solder paste, silk screens, etc.
Print shops can do this kind of work, too (precise amounts, sub-millimeter accuracy, irregular surfaces, almost any kind of coating, etc.).
They could, but when you open up a laptop where the manufacturer used thermal paste and you'll more often than not find it apparently applied with a turkey baster in a tenth of a second. Just a big old splat.
I understand that it doesn't make the system look better to a low-information buyer. So Lenovo aren't doing it. But Apply seem motivated to add small costs in exchange for moderate (if invisible) benefits.