I am a firm believer that dancing uncontested can easily become a "train wreck." While it is true that many uncontested events are marked as a first, I have seen (and have marked) many uncontested events as a 2nd and in some cases a 3rd. If I am judging I will NEVER automatically give a 1st in an uncontest event unless I truly believe the couple deserve it. If they are off time (or at least off time when I am looking) that is an automatic 2nd; if there is an obvious lack of technical skill required for the level entered then that is an automatic 2nd, if there is a combination of the two (and it happens in both pro/am & am/am competition) then I give a 3rd.
In an contested heat sometimes the 1st place entrant is the one who offends the least or put more bluntly the best of the worst. I have been in the position to have to rank three or more couples who lacked timing and technical skills for the level entered, quite a dilemma and found it very difficult to find a 1st place winner. If all couples had been "uncontested" they would have been easily all marked 3rd. But in a contested event someone has to be 1st, 2nd, 3rd and so on.
Don't always assume an automatic 1st in uncontested events, at least not from a qualified judging panel.