They don’t give a reason for this, but I assume it has to do with taxes. You see, if you pay someone $600 in any given year, you are required by law to report that earning and send them a tax form at the end of the year. And since 60,000 equals to $600, I assume they have that rule in place so they don’t have to deal with all that paperwork come tax time.
In a few cases, InboxDollars directed me to “exclusive offers” instead of straightforward surveys. One required me to give my name, address, phone number and birthdate to earn money and enter a sweepstakes for a Target gift card. Another time, I was prompted to give my email address and choose between Coke and Pepsi in exchange for $1 and a sweepstakes entry. I didn’t want to give my contact information to what appeared to be third-party sites, so I clicked out of these promotions.