[Symbiote]

Some people in Central Europe still use real candles on the Christmas tree. Of course, you place the candles carefully and don't leave them unattended.

(I have no idea how common it is, but I've seen the candles and brackets for sale.)

[Xylakant]

It is fairly common in Germany. There’s a special size of candles that fits those holders (Christbaumkerzen) and they’re a thing you’ll find everywhere in shops around Christmas time. I’ve never had a tree with LED in my entire life.

You must observe some safety rules, have a bucket of water or an extinguisher at hand (not under the tree) and never leave the candles unattended. And yes, be careful where you place the candles. Can’t have a branch that’s hanging over them.