Walmart and Target probably are a lot less concerned with accuracy than a fare collecting entity would be; any benefit from facial recognition is a plus for them even if it often either is wrong or fails to hit when it should, whereas with toll collection it has to be near 100% to replace other payment mechanism, and nearly never get a false hit (though misses might be okay) to be a convenience method when people are still expected to have a reliable method for on hand for backup.