Just curious. About where do you live? San Francisco or something?
Those labor rates kind of make me cringe a bit. They run about 75-80 dollars an hour at the dealers here and gas stations, etc. run about 40-45.
engine coolant is 50% water and does evaporate over time. there may be no leak or nothing in fact wrong. You didn’t check it for 2 years… or you wouldn’t have said “they might not have bled it two years ago”. Blame this one on poor maintenance habits and move on.
Power steering lines do leak, you saw the evidence of it with your own eyes. There is no warning light on any vehicle manufactured (that I know of) for low power steering fluid. You will usually know it’s low when it starts moaning and groaning when you turn, especially at slow speeds.
You can always get a second opinion if the quote seems unreasonable to you for the power steering leak repair.
And last, why did you “escalate to BMW?”, what was the perceived lack of service from your new service advisor? Is there more than one advisor at the dealership or typically there is a “service and parts director” or some sort of manager over the service advisors that would have been a better first step than calling BMW. That’s like calling Sony instead of going to Best Buy to return your TV.