This is information I find from academic searching. It never makes it into mainstream readership. Instead, we get false and out of date information about the need for drain holes and dirt. When we do get information about sub-irrigation it's almost always referred to by the inaccurate and misleading term "self-watering".
Most professionals understand the many benefits of sub-irrigating plants in containers. Why doesn't the public? The hard truth is that our horticultural education system is antiquated at best. Are you okay with that? I'm not!
From the USDA
A simple, inexpensive sub irrigation system can be made using children’s plastic swimming pools. This system supplies irrigation water more evenly to large deciduous plants in containers than do overhead methods, and it can be combined with a typical injector so that plants can be fertigated.
For those of us who grow broad-leaved plants in containers, we know that it is difficult to thoroughly, and evenly, distribute water because the foliage deflects irrigation applied from above. A hand-wand can be used to manually water such species, but this method requires time and personnel, and it is still difficult to obtain uniform water distribution. Sub irrigation can solve this problem (Dumroese USDA NRCS (2007) and others 2006); however, many sub-irrigation units are quite costly.