An electrical outlet or USB-C connection is more readily available to me than an Ethernet port with POE. Laptops aren't onboard because the problem of powering laptops is largely solved. Also...not many laptops have Ethernet ports.
Historic energy consumption is probably higher than classically POE supported.
Also, any length of POE run gets voltage drop, and POE switches and injectors often have tedious modal configuration based upon length of run and are designed with non-standard limitations such as maximum draw limits shared across multiple ports, which in aggregate will cause no end of issues. For verification, ask any experienced CCTV installer. These are exactly the sort of issues that cause users to take products back to their distributors.
So it's a case of "works in theory, PITA in reality, probable support and brand image impact huge, resulting priority zero".
That's right, but factories have other problems too: especially EMI due to huge loads being switched, which twisted pairs, shielded twisted pair and ethernet termination magnetics are designed to resist. Also, industrial cable routing can get pretty hairy, this means the ability to round a corner at a relatively tight radius can be important. Using standard ethernet cables for low current DC power keeps these concerns generally within acceptable realms of normality.
The more direct problem in my experience is that all kinds of network devices that could reasonably be powered that way don't support it. My Fritz!Box router and repeater don't support it, my Sophos firewall doesn't support it (tho the Sophos XGS can supply PoE it doesn't seem to be able to be powered that way either) and of course the Hue hub and Raspberry Pi can't be powered by PoE either.
