I suspect any US airlines saying "we sanitize our planes"
really means "we mop the lav and galley floor with a cleaner that contains* sanitizer"
(*when diluted properly by each of 100+ stations employing overnight contractors who may further subcontract the work to the lowest bidder).
Southwest is much better than some, and they have more opportunity timewise since their planes are parked overnight due to no redeye flights.
The ONLY planes getting a true hospital grade sanitation are the airlines flying back from Covid19 evacuation flights overseas. From what I read on airliners.net it takes 12-24 hours and workers have lots of protective equipment.