Finally I asked him, why he bought the car with low mileage when he knew he was going to use that for his long commute and when he knew cost was a constraint for him.

FORBES: Connect

Another huge constraint is the cost and availability of child care.

ECONOMIST: Out of sight, out of mind

There's no technological constraint on perpetual editing, and the cost of altering digital text is basically zero.

WSJ: Nicholas Carr on E-Books