Most apps and websites end up looking alike because the cheapest, lowest-risk way to build a working interface is to reuse a pattern that has already been tested on millions of other people. A product team rarely starts from a blank page. It starts from a design system, a component library or a theme, and those tools arrive with defaults already baked in. Sameness is not mainly a failure of imagination. It is what happens when many teams solve similar problems with shared tools and measure success in the same narrow way.
The fastest route to a working interface is a pattern, not an invention
A checkout screen, a login form and an address field each have a known job. Nobody gets credit for reinventing them, and getting them wrong is expensive, so teams reach for a proven solution instead. Design systems exist to package those solutions. The GOV.UK Design System collects styles, components and patterns so that services across government share one accessible baseline, and its stated purpose is to help teams build the same familiar experience rather than a bespoke one each time (design-system.service.gov.uk). The United States Web Design System does the same job for federal sites, with the aim of making it easier to build accessible, mobile-friendly services (designsystem.digital.gov).
Once many separate teams work from one library, their products look related even if they have never coordinated. The result is coherent, but the variation that used to come from each team inventing its own layout disappears on purpose.
Familiarity is cheaper for the brain than novelty
Attention is limited, and every interface competes for it. Recognising a pattern takes less effort than learning a new one, so products that reuse familiar structures are easier to use on the first attempt. That is the practical argument behind shared components: a user who has learned one form can complete another without relearning the basics. The same logic applies commercially. When a platform proves that a bottom navigation bar or an endless feed holds attention, rivals copy it, and the expectation hardens into a norm that new products are then judged against.
Measurement rewards the average
Product teams rarely decide by taste alone. They run variants and keep whichever one performs better on a chosen metric, such as completed sign-ups or time on screen. This is a reasonable way to decide, but the metric defines better narrowly. Layouts that are fast to parse tend to win those tests, because users process them with less friction. The winner then becomes the template for the next test, and each round trims a little more of the unusual. Over years, an industry that measures everything converges on a small set of shapes that are simply hard to argue with.
| Force | What it pushes toward |
|---|---|
| Shared design system | One accessible baseline reused by many teams |
| Testing against a single metric | The layout that parses fastest and converts |
| Ready-made themes and templates | The structure that is easiest to deploy |
Shared tooling turns one default into a global standard
The propagation step is usually documentation and code rather than fashion. Google’s Material Design publishes principles plus ready-made components for product teams (m3.material.io), and a single recommendation about spacing, colour or motion travels from there into thousands of separate products. Site themes and template marketplaces have the same effect at a larger scale. A designer builds a layout once, it is resold many times, and every buyer inherits the same structure without ever choosing it. A default inside a widely used library quietly sets the starting point for people who never made a design decision at all.
Where difference still lives
What converges is structure, not substance. Voice, editorial judgement, illustration, photography, the quality of support and the speed of the product itself stay hard to copy, and that is where brands increasingly compete. Some organisations also break the pattern deliberately, usually when their users have an unusual job that the standard layout handles badly. The interesting work has moved from the skeleton to the detail that a template cannot supply.
Bottom line: identical interfaces are the predictable result of solving common problems well at scale. A shared pattern library gets a product to usable quickly, and what it does with the time that saves is the part that still makes it distinct.