More common in the South, it being a poorer region most Southern counties had wooden courthouses rather than brick or stone. Not that brick courthouses can't burn (I know of a couple) but wood burns a lot easier!
I've hit a roadblock running the family of the man who sold me my farm . . . by family lore, they've had the land since it was opened to settlement, but Sherman burned the county courthouse here and the county was mostly hardscrabble farmers (we're in a not-quite-mountain region in GA and the soil is not ideal for farming!) so they didn't get the courthouse rebuilt until the 1870s. Heaven only knows what happened to any land deeds in the interim. But no records before 1884 (maybe people got out of the habit of filing deeds! But GA is a "first-filed" state, so most folks file right away.)
I love the old wooden Southern courthouses. The one in Bartow county to the south of you is still standing and a true gem. I’m trying to remember which movie filmed courthouse scenes there, but coming up blank. Not “To Kill a Mockingbird” but similar famous old movie. Guess I’m having a case of the “Sometimers” lol.
Take a look at it if you pass through Cartersville. It was replaced in 1869 with a fancy brick courthouse and no longer in use as a courthouse, but a true gem of an old Southern wooden courthouse. The inside is quite impressive, at least I found it so.
You feel such a great respect for the majesty of the Rule of Law and right to a trial by jury in those old courthouses. Like the people then took it very seriously, far more seriously than we do today. So different from the modern courtrooms that feel like a modern university classroom or something. I believe our architecture has a real effect on us, as well as reflecting our values.
The trouble with them, as you pointed out, is they could and did burn down. :( I had a similar problem with burnt courthouses and missing records in the Carolinas.