Perhaps this is not a widespread issue but it seems to have happened to people I have referred, where we both do not get the referral credit as expected. Don't worry, Ting has always made it right for both parties for the ones I am aware of... but maybe there is a simpler solution?
I believe the problem is with keeping the referral in a browser cookie until purchase/activation... I think what happens is that someone uses the referral link, creates an account, but then either clears their browsing data or uses a different browser, computer, or device when they actually buy a Ting phone or activate a BYOD phone.
Obviously the referral should not be fully credited until the person buys or activates a phone, but it seems like it would be pretty easy to note that the person has been referred once they create an account on the server side rather than leave it in a cookie on a single browser. Most people use multiple devices these days and especially with BYOD they may not realize that the referral credit they thought had been applied to their account isn't there anymore until after activating their first device.
Basically what I am suggesting is the way most referral programs work: a person uses a referral link → they sign up → the credit is attached to both accounts (but not yet applied) → then once the person who was referred does x (in this case buys/activates a phone) the credit is applied to both accounts.