Recorded sound below 30 hz is pretty rare. 20hz is the lower audible limit of human hearing. So most people do fine with 30hz and those who want every possible scrap of frequency response would want to reproduce 20 hz. You can feel content below 20 hz but you can't actually hear it.
Recorded sound 30 Hz isn't rare actually. In fact, many sound recording engineers employ 20 Hz high pass filters on everything, because of all the incidental low frequency stuff that gets on the recording, like a gust of air on the mic from somewhere. But I think your point is it is rare in commercially available recordings, which is true.
You can hear content all the way down to the single digits. It is a fiction that people can only hear down to 20 Hz, that is a rounded number for convenience.
Here is an essential article for anyone interested in the lower extension of human hearing. The low end of human hearing looks to be 2 Hz, not the oft-quoted 20 Hz. That basically gives us about 3 more octaves of hearing than is commonly understood! In reality you are hearing extreme deep bass all the time, just roll down your car window when driving down the freeway, or stand by a freight train as it passes, or on a runway with b-52s landing or taking off. The most palpable tactile bass seems to be mid bass frequencies by the way, not deep bass frequencies, although deep bass frequencies can be felt too, with enough amplitude. Here is the money shot of tested hearing down to the deepest frequencies:
Here is all of those low frequency hearing studies averaged out; this is a proposed extension to the ISO 226:2003 equal loudness contours, which only go down to 20 Hz:
