Maintenance cost is extremely high, always in loss

maintanance costs per aircraft type grouping does not differ per world.

You could post more screenshots of two different worlds with different prices.

PS: aircraft age affects leasing price.

I have never encountered such an issue, Are you playing in a special world, or could it have something to do with taxes, idk, I am just bouncing ideas but please provide some more evidence, otherwise, frankly I think it is good, this world could become another challenge world as it is reall easy to set up a functioning airline in all of the realistic worlds. 

There is a bug. The montly maintainance cost that is reported in Airline Finance, is the year mantainance cost.  Differs from the monthly mantainance cost that is in the Aircraft report. Please fix this. 

The reason for high maintanaince costs as far as i can see from the picture provided is due to the operation of 2 different aircraft families.

Although the costs per aircraft may not be that different in maintanaince cost, the base cost per family do varry alot and do result in higher maintanaince fees if you operate more types.

Also as aircrafts gets older they tend to get more expensive to operate wich is why the maintanaince costs (per aircraft) also rises.

It is a bit hard to see, but it looks to me as if you've got a lot of long range aircraft at the start of the game. This can make it very tough and I'd advise agaisnt it, especially if your airline is based out of a smaller airport