Why did they build so many of these before they tested and redesigned them? They saw that coming and could have saved a ton of money by making just a couple each time.

Great , the Australian Government is spending 24 Billion on these Jets & slashing Health, Education & numerous other vital services ....

A few billion here, a trillion there. Pretty soon you're talking BIG money.
Seriously though, isn't there something wrong when that kind of funding is allocated to designing destructive weaponry, but trying to understand some basic science that might address, for example, ocean de-alkalinisation, is met with budget cuts and apathy. Fear rules.

@johanschaller
The Brits have just had the naming ceremony of a massive aircraft carrier designed to operate these aircraft. It is already going to have to have it deploy helicopters instead due to delays with the F35; delays which I assume have just been extended thanks to the fire and subsequent grounding.
It is not as though having large capital ships to operate such aircraft off makes a lot of sense anyway now that supersonic cruise missiles are being deployed, not to mention atomic depth-charges, which I assume have a an anti ship mine equivalent. The latter two feasibly deployed by terrorists in the form of IEDs once they get their hands on battlefield nuclear weapons. Pop one of those off in the Western approaches to the English Channel and the results would be spectacular in the extreme, especially considering the amplification from the funnel shape of the topography. (Imagine a 65,000 tonnes displacement aircraft carrier one minute happily moored at its home port and the next minute beached in the middle of the town, along with a number of other ships. As I said: "spectacular".)
Another quote worth remembering and closely related to your first sentence is Bob Dylan's: 'money doesn't talk, it swears' - from It's Alright Ma (I'm Only Bleeding).

We're just lulling them into a false sense of security.
Keep that under your hat.

The problem with the F-35 (including the B variant) is that it is incredibly easily nullified by the Piper Cub Paradox. The expense of the aircraft is just too great to make sense.
In the Piper Cub Paradox, you pit a fighter aircraft with all possible stores (guns, rockets, etc) against a Piper Cub (which can carry exactly one AAM and the associated electronics. You take the cost of the one fighter (around $300 million a copy and around $50 million a year for fully booked costs.) And compare it to the number of Piper Cubs that you can manufacture at $8,000 a copy and around $50k a year fully booked costs. In any sort of simulation the Piper Cubs will always win because of sheer numbers.
This might not seem germane, but both the Russians and Chinese are set up to neutralize high-tech fighters such as the F-35 with swarms of MiG-15's, 17's and 21's, with an increasing number being remotely controlled drones. This is the Piper Cub Paradox in the real world.

I know that DARPA is working on the problem of "why does it take an auto maker a year and a half to rework a production line, while aircraft mfgs take a decade and a half". Let's look into our F-16 program playbook and see how to build an affordable, but brilliant aircraft. The '35 was doomed from the start. If the marines want a vstol, then make a really expensive plane, say $150 million, just not many of them. The rest of the crew gets $50 million planes, and more of them. Its going to get to the point where they could have just bought more '22's for the same money. uuugh. Silly Pentagon.

In the 90's the clinton administration deleted several Mil-Standards claiming cost savings, availability of commercial practices, standards, and streamlining development. Some of these deleted items were related to testing. the intent of these standards was to ensure a reliable military product. Both the F22 and F35 have suffered from release of a product before it was ready. this works great for the aerospace companies but not for the USA.
Let me suggest that we need more development and testing standards to assure a finished product and lower cost.

That which a nation grants to be of importance in what it makes is best reflection of what that nation embodies.

I need them to send me 3 million dollars, so I can help! ;)