There are two ways to pay for riding the Metro - tickets or Nol cards.
Looking at the prices to ride the Metro, its quite reasonable. If you choose to drive then you're paying for petrol and also Salik (I learned that by avoiding Salik I ended up paying more in petrol) so makes sense to use the Metro. Where the prices become unreasonable is when you start travelling different classes such as Gold class which has nicer compartments with wide chairs and all the other things you would expect from a Gold class.
The RTA did a good job of not making the Metro overly priced, the costs are reasonable and affordable. Here's hoping that the RTA doesnt change their mind and put the prices so high that it becomes unpopular and everyone starts using their cars more than before.