I'm going to stop posting in this thread. Because I am too biased.
Right now I'm sitting in my ranch house, looking at my barn 100 feet away. It's the barn served with undersized small wire and with crappy power, where I can't run a welder or anything too much past a light bulb. There's no low voltage wire or low voltage conduit-- gosh-- I wish I could put an alarm or CAT5 camera out there. Or maybe a mesh wifi device. And no water-- no schedule 40 pvc-- so I have to come into the house when I'm all dirty and foul things up in the house just to wash my hands. Or for the many other uses I would use water in a barn for ..... maybe water for animals? Radical thought, maybe?
But ... whoever preceded me and put in the undersized wire with direct bury saved some really good $$ back in the day. God they saved a lot not putting in a conduit. Wow, I hope they saved a ton! And as a bonus, they put a low-end cheapo Zinsco electrical panel in the barn-- you know, the cheap ones known to start fires because the breakers don't trip even when overloaded.
I have a tractor with backhoe, so I could fix it by trenching. But, the thought of digging up the old cheapo wire and running new conduit isn't pleasant. To trench again, I need to go through established flower beds with large plants, front yard lawn, a substantial amount of gravel driveway, and through roots from 100 foot tall oak trees that can reach 8 inch diameter or even bigger.
So ... I live with it because the effort to install conduit doing in the right way ... after the fact ... is too onerous.
But ... the original installer with the direct bury cheap wire--- saved some really good $$$.