To be fair,
One must also look at seller pov.
Once the owner received the earnest deposit, the owner cannot sell to other parties already.

If every buyer act the same way by giving earnest deposit then after 1 month later decided to buy and cited those trivia matter, then seller wasted another 1 month and potential lose of opportunity to sell other party already during the 1 month loss.

Paying earnest deposit means one is sincerely want to buy the property already and tight up with the seller.