I'm no United lover, but UA have been very friendly to me before and SouthWest not so.

In my case UA agreed to changed my flights out of Shannon to out of Dublin due to family issues at no costs. Granted there were no day changes but it was not required they do so.

In another case southwest refused to,let me go standby on the same day unless I payed a hefty fee.

My point is for both airlines you'll find some employees going out of their way or not.

You can't reason from one data point to reach a conclusion.