AV, if your local mall started charging for parking, you'd simply drive to the next mall. Now, if all the mall owners put their greedy minds together and said we're all going to charge, you'd be pissed for awhile, but in time you would'nt even give paying it a second thought.
And as others have said, you may not be paying for parking as a direct out-of-pocket expense, but it is included in the price of the products you buy in the mall. But of course we all know that if malls started charging for parking we would'nt see the shop owners drop their price.
WDW was the first to arrive in Orlando. From day one they charged for parking. Every park that opened afterwards charged for parking. It became SOP for the industry.
Disney pays a lot of manpower to operate a parking lot. Drivers,security,toll takers,people that direct you to your parking spot,people that clean up the lot at nite, people that maintain the rain water run off canels, fix lite fixtures, landscapers,etc. Repaving,line painting,trams,vans,electricity,gas,etc all cost money. A parking lot is not a minimal expense. I don't believe a parking lot should be a profit center, but it should be self sustaining and not a drain on the parks - Disney has ABC for that.
Disney also uses that parking fee as a marketing and sales carrot. Buy an AP, don't pay for parking. Stay on property, don't pay for parking. Buy DVC, don't pay for parking.
Considering all the people who park without paying and all the real expense to operate the parking lot, I really don't think Disney is increasing shareholder value by charging $9.00 to park.