Why would you log taxi time? That's retarded. Not sure how airlines track maint flight hours, but if it's like the military, by logging taxi time you're adding additional hours to the airframe that weren't actually flown, thus pushing it into phases earlier, inspections before needed, and thus costing money. Plus you're now a pencil whipper. I've never logged anything that didn't involve getting air under the tires. If I could have every maint cancel I could probably add another 100 hours... but it wasn't "FLIGHT" time.