Suppose you know that for our health, shortbread is better than muffin. By that, substituting muffin with shortbread in our diet is good. Yet, many people, as they love muffin, understandably, will not alter their diet to shortbread by persuasion, even for the noble purpose such as public health.
In anticipation to that, the cafe introduces more shortbread at low price, and due its limited capacity, they can not provide you with muffin as many as before. And, it's a small wonder that muffin eaters grumble. They complain that muffin is now hard to find.
But on the second thought, wouldn't it be the perfectly predictable, and desirable, effect --to make the muffin relative price to shortbread rises? Sooner or later, they will respond and switch to shortbread, and as time goes, switching will be less painful.
Now, replace health, shortbread, muffin, the cafe, muffin relative price increase, and switching responsiveness; with travel time, the busway, driving your private car, Jakarta busy thoroughfares,traffic jam, and elasticity of substitution. I hope by now you get the idea, thanks to Econ 101.
Oh, and the muffin eaters/grumblers, they are the popular voices oftenly appear in newspapers, TVs, and, well, politicians' words. Just want to say: come off it, mates!