Something to consider is the condition of each fluid. Steady state hwy driving is far less hard on the oils and the debris / wear put into the oil is far less as well. On the other hand if you only drove 2-5 miles to work the fluids never really get a chance to get up to temp. You'd also be more likely to have more stops and starts.
So 50k miles is not just 50k miles. It really depends on how it was operated during that time.
If I'm not mistaken most owners manuals note this too.