Network Solutions (and others) were abusing a 5 day grace period in which refunds were available. Ostensibly this was to address typos and mistakes. Domain squatters would also abuse it by registering thousands of typos and random word combinations names and use the grace period to get a 'taste' [1] of traffic. If they thought they could monetize the domain, they'd keep it.
Unfortunately, they can often use the 'trial period' to register the domain after you search for it and then 'return' it a few days later to avoid having to actually pay for the domain.
