CarMax review: worn steering column

I purchased my 2015 Toyota Corolla from CarMax in Glencoe, IL in January 2017. Between then and September of 2018 I had taken the car in multiple times for steering wheel issues - I was told the steering column and gear were replaced, the alignment was checked, etc. and each time the problem would come back within days to weeks. Even though I had my warranty through CarMax ultimately in November 2018 I took the car to another local mechanic who checked the steering column and told me that as soon as they got in the column looked as though it were about to fall apart in his hands. The column was replaced and the problem has been resolved. My question is what the hell was CarMax doing this entire time the steering column was bad? I was told this was a huge safety issue that could have become a really bad situation had it not been fixed. Clearly they either never checked the steering column or they checked and did nothing to fix it as they were being lazy (the car was under warranty so I wasn't opening my pocketbook, hence they decided not to care). Thanks for nothing CarMax.