How come phones crash - surely they get tested thoroughly?

Having worked in software testing I know you can't iron out bugs in all software but is the lead time and product shelf life of a phone so small now they just don't bother with plugging the obvious software problems, or as not their own OS (android etc), there are hardware/software conflictions? 
 
Borrowed a new Blackberry Torch off a friend to test and bloody hell the thing never seems to stay on!!

^^^ suspect its a mixture of both... the technology moves so fast that if you put off releasing a new phone for 6 months to make sure its tested 100% bug free then its no longer state of the art when it hits the shelves... you've only got to look at handsets from 4 or 5 years back - look like museum pieces now. When the pressures on to constantly stay ahead of the game with the 'latest' tech then inevitably its going to get rushed out to the consumer with a few corners cut
 
Plus, as you say, the hardware manufacturers dont usually have control of the software... and may not have full control even of all the hardware (with different components out-sourced from various places)

I think it is down to needing to be powered down occasionally to "reset" or something. People rarely turn their phone off unless it goes dead etc.*
 
*This is brotechnology at its best!
 
 

It's a BlackBerry.
 
 
Seriously though, I've used my brothers and hate the damn thing.

Umm BB are pretty much the most stable of the OS's, hence every emergency service around the world will only use them and nothing else, Droid was by far the worse, and strangly its Google that have no control what phone uses droid, spec etc.
 
I would say theirs a hardware problem or sommin out of the box that was wrong with it.

they do test them but i guess they can't test every eventuality, such as which app was installed first then 2nd etc - which app conflicts with other software running or if it's been dropped.
 
it might have been made at 4:45 on a friday