In coach, when they were built 30-40 years ago, not everyone had cell phones, laptops, DVD players, GPS, etc... - thus 2 outlets per car was enough for the cleaners. As the cars go in for refurbishing, they are adding power-at-seat. I would say the chances are 80-90% of finding at-seat power in coach!
Is the proportion really that large? The last four times I've taken coach on the Empire Builder, my car hasn't had outlets. Maybe I've just been unlucky, or other trains get the refurbished coaches.
Based on my last trip in August, I said 80-90%.
On the CS, I went coach PDX-SAC (although I ended up staying aboard to OKJ) in coach. The seat that I was first assigned to did not have at-seat power. So I walked the train. The car behind also did not, but the 2 coaches behind that did! I asked that CA, and was allowed to change seats!
Most of my (many) other trains that trip, I was in a sleeper. But I did walk the trains, and a large percentage of them had power. Not all, but most did.
On my many trips this past year, I have always had at-seat power!
So I'll stick to my 80-90% estimate!