I continue to be amazed that people send me uncrossed postal orders through the post. Doing this is just an expensive and time consuming way of sending cash. Anyone can walk into a post office and cash an uncrossed postal order. They might be asked to sign their name on the back, but its hardly difficult to look at the name before they go in and "sign" that name. I've never been asked for identification.
Another advantage of crossing a postal order is that it has to go into an account and hence is traceable.