>those people fixing the roads are incentivized to do the work cheaply

this incentive exists with or without corruption

cheaply as in not meeting standards

without corruption you could do a shitty job once and then you won’t get another contract because you did a shit job

with corruption the quality of the work won’t matter so in the extreme case you can deliver nothing at all and you’ll still keep getting contracts - In my country we call this being “plugged in”