Quite right, normally the aircraft manufacturer will compile an M(aster)MEL, this will be ratified by the National Authority, the CAA, HKCAD, CASA. The NAA then issues a MMEL list for a/c types.
The MMEL can be added to by the operator (with authority and ratification by the NAA) but can not be reduced in content, or the NAA.
Essentially what you should see is an MEL produced by Boeing or Airbus added to by the NAA or operator so in essence every airlines MEL should look the same except for certain peculiarities to that airline.
In HKG CX wanted to reduce the time limit for D category items, 120 day time limit to 60 days, which it did with authority and approval from the NAA. We wouldn't of been able to increase it from 120 days though as this would be a reduction of the MMEL and not an addition.
We have also where MEL's are confusing/grey! areas changed the 'notes' etc to be more explanatory.
At the end of the day if you're not happy or are confused about the MEL then you don't have to take the a/c, of course I will pass you a mobile to call the powers that be as it's now not a Tech delay but an operational one
Having read, used and interpreted MEL's for a number of years now, I always read it twice, looking for the and/or's/but's and maybe's, first to understand it secondly how to get around it.
It's suprising what difference one little word makes.