Sounds unfortunate, but they are not a scam. The issue is all about personal responsibility. it's really very simple, the warranty covers your vehicle for these repairs, all you have to do is get a warranty approved oil change at this interval and keep records. She didn't, hence the declination of the repair.
To bad she didn't read and follow the warranty requirements, it could have been a different outcome.
In my personal experience, every aftermarket or extended factory warranty here in Canada has the exact same requirements. Yes it can be a pain, but every warranty contract has rules. With how cheap a basic warranty oil change is, their really arent many excuses not to do it.
Not trying to be shallow here, but I get tired of people trying to chuck their own responsibilities and blame someone else.
She made the mistake, learn from it, get over it and move on.
To quote from the article:
"All in the Fine Print
An Interstate spokesman directed us to the contract, which states you must save every oil change receipt, and be able to prove the oil was changed every 5,000 miles.
In addition, those changes must be done by a commercial facility, not by a family member, something Henn says she had done a few times to save money.
"I've been able to have my husband do it, or my son do it," she said. But those money-saving home oil changes may have voided her warranty."