A dozen markets wearing one label
Each major European market has its own competitive ecology. Germany rewards depth and formality; its agency scene (and its buyers) expect engineering-grade documentation. France runs on editorial relationships that outsiders rarely penetrate quickly. Spain and Italy have younger, cheaper agency markets with wider quality variance. The Nordics are small, English-friendly, and deceptively competitive because everyone is digitally mature.
Google's share exceeds 90% in nearly every EU market, so the algorithm is constant; the inputs are not. Keyword demand, SERP features, link availability and even content-length norms differ per country. A pan-European campaign is really N campaigns sharing a tech stack.
The network-agency compromise
Big networks solve coverage by acquisition: an office (or partner) per country, quality varying by office, coordinated through account management you pay for on every invoice. It works for enterprise budgets. Below that, coordination overhead eats the budget that should buy content and links.