I don't think the issue is dynamic pricing but the app's UI. If it said "We'll be charging you $50 for this trip" instead of "The rate will be 6.5x than normal"

I don't think the issue is dynamic pricing but the app's UI. If it said "We'll be charging you $50 for this trip" instead of "The rate will be 6.5x than normal", users would not have taken the ride. If the UI was right, the prices wouldn't have increased to more than $50 per mile since demand would have likely decreased when the rate was about $20 per mile.