I have an extension cord reel (50 feet of cord with 4 x 15 amp outlets on the side) that has an ETL label indicating 11 amp, yet the breaker on the cord reel specifies 15 amp.
It is 14/3 SJTW cord.
I can not upload attachments here to show you exactly what I see, but this is a fairly common cord reel available at home improvement stores.

The question is, how can we have at 15 amp reset on an extension cord that is "rated" at 11 amps?

14 AWG copper conductors are listed to carry up to 15 amps.

Usually you do not want to load a cable greater than 80%, which would be 12 amp. Just speculation, but the manufacturer of the cable wants to keep you well within the safety margin.