They do tests and destroy stuff, but they don't sacrafice a whole plane like in the old days. They have enough data so that "if its fixed, don't break it"
One of the great things about living in Phoenix is that Boeing does heat testing of new designs here in the summer. We got the first 747-400 and the first 777, it was cool to be able to see them coming in and out on a blazing hot day.
As for the ripping of Airbus, yeah, its irrational, good thing everyone here likes Brazil, otherwise Embraer would be villified!
The FAA and JAA (sorry, I said CAA earlier) review the design submittals and work with the manufacturers to ensure the necessary tests are done to achieve an Airworthiness Rating. This includes calling for demonstration tests on any new or uniquely designed areas of the plane. If that means that the design is "new" enough where there is no existing data to rely on, then a full-scale test can be called for. Believe you me, I sat though enough design strategy sessions trying to pencil whip a design to the point where it is "similar enough" to an existing one so that a high cost test could be avoided. There haven't been as many full-scale tests because there haven't been enough all new designs coming out of the box - most are derivatives of existing ones so that similarity can be claimed.