Most local searches, and nearly all "near me" searches, happen on a phone, not a desktop. Every site is designed starting from the mobile layout, then adapted up to tablet and desktop, rather than designed for a big screen and shrunk down afterward.
That distinction matters more than it sounds: text sizes, tap targets, menu behavior, and form fields all behave differently when designed mobile-first versus retrofitted, and it shows in how easily a visitor can actually find your phone number and act.
What's included
Why it matters
Google evaluates the mobile version of your site for ranking purposes by default (mobile-first indexing), and a majority of local traffic arrives on a phone. A site that merely "resizes" on mobile without being genuinely designed for it usually shows the cracks exactly where a customer is trying to call you.