I must say, telling people to use the PAID credits to get around this is a cop-out. I don't feel like spending $100s on this game and I should not be punished for that, neither should anyone else. It's just a way to force people to buy the credits. I get the argument is to "keep it challenging" but this is a little browser game with a niche community. No one should have to pay to win here because the game makes it too hard to expand after a certain point if you're not sitting here trying to grind away all the time.
You have another option instead of using coins and that is to discontinue play. The cost to expand is not going to change and they have proven they are going to continue to add stuff that "costs" such as the new urban and rural extensions, the equipment and traffic control stuff last year and so on. They are in it to make money not to let us all play for free... Sorry to say that, but it is real life.