The overhead lines into your house are too. The line connection into your breaker panel is aluminum.
The "overhead line" is underground, from the nearest substation. Which, come to think of it, has no overhead lines into it either, so it must be supplied underground too. We do things differently to America.
And the Earth and Neutral lines coming into my consumer unit (different terminology too) are definitely copper. The Live line terminates within the supply-company's fuse block, so I can't examine that without breaking the tamper-evident seal.
The "last mile" of power distribution here is largely underground in urban districts, so weight-on-pole isn't a concern. (And for decades, we've been pushing telephone lines etc underground too. Dad's house was "telephoned" in the mid-1970s from a pole - and the roadside trees have snagged the line at least twice since then ; but no house I've owned has had telephone lines on poles. (1980s wiring?)
Different country, different choices. I'm not sure when (if, even) a decision was taken to go for underground distribution instead of on-pole here. Maybe in the aftermath of WW2?
My first career was mineral processing at a mine. A promising career in 1990, dead on its ass by 2000.
No first world country likes to have dirty things like mines around. Or, for that matter, the oil wells that fuel their cars - they like them decently over the horizon, out of sight from beaches with built-in hypothermia. The only metals mine to open in the country in my lifetime went bust about 18 months ago - just after I'd applied for a job there.
It's so much more civilised to buy processed materials from foreigners ... until the foreigners start to manage the prices for their benefit, not ours. The barbarians!