One of the providers[0] in Sweden: 8 GB data - $7.52, 25 GB - $12.6. $17.6 for 100 GB. All accounts carry over unused data up to 100 GB indefinitely. 13 GB data anywhere in EU/EES.
UK is probably the cheapest market relative to GDP per capita. Three offers unlimited data, calls, texts and roaming with no throttling including 5G for £17/month.
Actual competition is a hell of a thing. I'm pretty sure there are some backroom price fixing agreements between the Swedish operators, the profit margins wouldn't hover around 30-40% if there wasn't.
There were some dawn raids on these companies last year by EU antitrust authorities, but they didn't find any actionable evidence. :/
[0] https://www.hallon.se/mobiltelefoni