Transit costs in Seoul run fifteen times higher than Frankfurt. South Korea's government mandates commercial interconnection rates based on predetermined network tiers, giving incumbents pricing power that settlement-free peering elsewhere would prevent. When you're running browser fleets globally, this isn't trivia—it's operational cost shaped by economic structure.

The internet's cost hierarchy traces to a consolidation moment in the early 2000s. What changed wasn't the pipes or protocols. Something about who controls network access and what that position is worth crystallized into permanent infrastructure. Anyone building distributed systems at scale navigates the consequences.

Transit costs in Seoul run fifteen times higher than Frankfurt. South Korea's government mandates commercial interconnection rates based on predetermined network tiers, giving incumbents pricing power that settlement-free peering elsewhere would prevent. When you're running browser fleets globally, this isn't trivia—it's operational cost shaped by economic structure.

The internet's cost hierarchy traces to a consolidation moment in the early 2000s. What changed wasn't the pipes or protocols. Something about who controls network access and what that position is worth crystallized into permanent infrastructure. Anyone building distributed systems at scale navigates the consequences.

Luke Wroblewski's 2009 mobile-first design philosophy looked like salvation when smartphones started eating the web. Google pushed it hard. By 2016, mobile traffic had overtaken desktop.

Nobody saw the desktop problem coming. Optimizing for small screens first doesn't scale up gracefully. It creates "content dispersion" on larger displays: bloated text, screen-covering images, excessive white space, endless scrolling. Accordions that collapse information efficiently on phones become interaction nightmares on monitors, fragmenting content without the space constraints that justified them.

Mobile is 55% of web traffic now. That other 45% navigates interfaces designed for a different context entirely. Every responsive system must solve for two fundamentally different interaction models, not just different screen sizes. The infrastructure cost compounds daily.

Usability research: Nielsen Norman Group's 13 qualitative tests found content dispersion increases cognitive load and creates difficulty understanding content on large screens.

Traffic split: 55% of worldwide web traffic comes from mobile devices as of 2022, meaning nearly half experience interfaces optimized elsewhere.

Accordion problem: Design patterns brilliant on mobile by collapsing information contribute to content fragmentation on desktop, significantly increasing interaction costs without benefits.

Google's push: The 2015 mobile-friendly update boosted rankings for mobile-optimized pages, accelerating adoption of patterns that would create desktop challenges.

Design constraint: Responsive systems must now solve for two fundamentally different interaction models, not just screen sizes but entirely different behaviors.