Thanks for pointing it out, and ya its really hard to do. I think you identify certain signals and do the best you can in your interview process to flesh them out, for example:
1) History of working remotely successfully in the past
2) Strong verbal or written communication skills, i.e. ability to explain complex ideas concisely or to break down large ideas into consumable smaller ones.
3) Higher education background, indicating the ability to push through benign task and consistently reach performance goals (c's get degrees)
4) Aligned long term-goals for example, engineer foo wants to hit a certain salary level by gaining an expertise in $tech_x, and at the same time your company has domain experience in $tech_x that could facilitate for your employer
5) Ability to break down past projects in the context of "how would you do it differently with a do-over" or "what are some examples where you mismanaged technical debt"
None of these ideas are perfect, and execution in the interview is perhaps the hardest part. I myself am a college drop out which makes it ironic that I would suggest people with degrees make for better remote workers, but when it becomes a search for signals a degree from certain tiers of universities is too hard to pass up as a hiring manager who just wants to do a good job.