All kits i have had over the years, and other have noticed, the kits are identical all built on the same production line just a differnt box at the end.
My £25 ones lasted years and are still going now in my old cars headlights.
You can not be more wrong.
All HID's are not the same.
There are hundreds of different factories & thousands of different ballast & different technologies.
Some HID kits fry the wiper motor & some don't.
What you are saying is just like saying all OEM HID are the same.
And they are not, different factories & different technologies again (D1S, D2S, D3S, D4S, D5s, D6S)
Integrated starters, not integrated, AC ballast, DC ballast, mercury free bulbs, not mercury free, 3000 Lumens, 2000 Lumens...
I could be all day telling you the difference between them.
This is why you can find £25 & £200 HID kits.
And no, again they are not the same.