Obviously this person has at least 12 non payment strikes so how can they continue to bid???

obviously they do not have 12 strikes, some sellers do not follow through. 

I am assuming that you do have your blocks in place?

Saying all that, there might be legitimate reasons why some people lately won items and did not pay.  Remember floods, fires, storms, power outages lasting days, over this summer?  In this moment there are many people in Victoria on notice as more fires have broken containment lines.  While my friend in Townsville is talking about torrential rain with road closures.

I think it is a good idea, when somebody does not pay, to have a look on map and see if there is anything happening/happened over past week in their area.