mriya225,
All major airlines review manufacturers and vendor service bulletins.
They are reviewed to see if they achieve:
a)better dispatch reliability, or
b)lower operating cost.
They do not include safety in their reviews hence the AD system.
How many passenger do you know that say I always fly xxx airlines because they put safety first?
You only have to see the increase in booking on the Internet where the only criterion is cost (and perhaps timing) but not safety !
It is also interesting to note comments about Europe (particularly UK) and USA. There are still "Special Conditions that have to be complied with a fully FAA certificated aircraft before it can fly on the UK register. There are modifications and even a different Flight Manual with different perfomance. Do the average punters care about this?
No ! only price.