How do telegraph poles work out in the sticks?

This is going to sound like a really dumb question but the village where my grandparents live is way out in the sticks and is fed broadband and telephone via telegraph poles which travel for a good 2 miles if not slightly more ALL the way back to the slightly bigger village.

Recently, a car hit one of these poles and as a result the cable had to be cut, resulting in the 80 odd residents and a number of businesses in the village having no internet or telephone. The cable has since been repaired and they are all back online but it got me wondering, how do they all manage to get 4Mb broadband?

I stopped to have a look at the cable and it's not very thick at all, maybe the thickness of a HDMI cable if not slightly less. The further away from the exchange the slower the broadband, but if the broadband is provided via one cable how does that work as surely that one cable would be a bottleneck (if you had an 80 lane motorway and it suddenly merged into 1 lane, it slows down for everyone)

I did think that maybe the black cable was actually a sheath that just covered loads of smaller cables but it didn't seem anywhere near thick enough to carry the connections for more than 80 residents. I'm also pretty certain it's not a fibre cable either and I don't believe BT use coax?

It has really got me puzzled as to how everyone can get online at the same time so if anyone can explain that would be great!

HDMI cables are usually only 4 to 6mm thick.

50 pairs is I think around 19mm diameter which if estimating from the ground while a fair bit bigger than a HDMI cable might be the real diameter (100 pairs are slightly more thick at 24mm (assuming 0.5 mm conductor, if a thick copper at 0.9mm increases to 28mm for 50 pairs.

Copper phone lines are dedicated to each customers, so there will be a pair back to the location where the broadband signal is injected and telephone service.

That 1 cable you see on the telegraph pole is a multi pair cable.
It has 10/20/50/100 (and many other sizes) "pairs" of copper cable inside.

Your grandparents broadband only uses a single pair.