Agreed. Consulting and working with individuals to develop their 'baby' is extremely difficult. Majority of the time their expectation is that coding is fancy typing and changes take seconds not hours.
As a developer I would suggest building in a reasonable monthly fee for X months for support. It's unrealistic to assume apps are going to meet customers expectations 100% of the time. Discussing this and setting a budget for after 'completion' helps a ton.
The poster and most individuals expect to pay a one time fee and start making tons of money on their idea without reinvestment.
As developers we need to help educate clients. But, individuals are hard, we never do it unless they are well funded. Not just for their app but for their marketing and overall initiatives.