One of the things I keep coming back to is that Intel seems loathe to customize any of their process tech solutions towards a balance of maximum power efficiency and overall compactness. As we have seen with almost every mobile arm solution out there, each process node and design rules set that they use optimizes for power and density first, then tries to squeeze out as much performance as it can afterwards.
Because that's a tradeoff you are forced to make. If you want higher performance you use high performance transistors, but those use more power and more area. Intel could use lower power transistors and "optimize for power and density first" but they'd have to pay for that choice by reaching a bit lower max clock rate.
The tradeoff is obvious for ARM designs which are almost entirely used in mobile (or smaller) devices where power draw is paramount. It is just a happy coincidence that optimizing for low power also optimizes for density. There would be some more interesting friction for phone OEMs in the choice between low cost and low power if lower power implied lower density instead.
I don't know the degree to which the process itself (rather than the parameters you tweak in e.g. the transistors / cell libraries) can be slanted one way or another. Probably not much, given how flexible TSMC's recent processes appear to be. If you think Intel is choosing incorrectly, they aren't necessarily choosing wrong when designing their processes, but rather when they are choosing the parameters to fab a given design.
Intel has competed on performance for decades, they are very comfortable doing that so it is no surprise it continues to this day. They've never really competed on power - as far as low power goes their marketing only does comparisons with Intel's previous generations. What AMD is doing power wise doesn't matter to them, and ARM is totally irrelevant to their market. In the PC world consumers mostly don't care - they buy a laptop for x number of hours of battery life, not 15W TDP. As far as laptop buyers are concerned, it is the OEM's problem to figure out how big of a battery is needed for whatever Intel spits out.