In Japan, the default assumption is that unless you're in a very rural area, everyone goes everywhere by public transit. Even if you're just heading to downtown Tokyo from Narita airport, the Skyliner will be faster and cheaper than a taxi. Furthermore, you probably aren't taking a taxi from one prefecture to the next.
Yet I never see Japanese people with luggage on trains, whether that be an airport train or the subway. I'm pretty sure everyone takes a taxi or an airport bus when they have luggage.
I did consider that, the other factor is Japanese people travel for smaller periods of time so maybe carry tiny suitcases instead of the (multiple) huge ones you see foreigners carry.