I'm sure this will be an unpopular opinion, but you've always been required to report any profits from any sales you're making and pay the relevant taxes on them. The government just realized how many people were cheating, and because PayPal has a record of all the transactions they're doing the government required them to send the records direct to the IRS on a 1099, in effect forcing people to follow the law they were breaking previously by not reporting the sales themselves.
All these different cash transfer apps have records too, which means eventually the laws that now apply to PayPal will likely apply to the new apps as well. Only a matter of time, those apps have records. And even in the meantime, if you were directly investigated the IRS could probably demand those companies to hand over those records, even if they're not putting them on a 1099 like PayPal is now required to do.
So maybe you can "get away with it" for awhile with a new cash transfer app, but eventually the law will catch up again.