For decades the cheap airfare came with a catch: you had to stay over a Saturday night.
That rule had nothing to do with aircraft or crews. Airlines needed one fact about you. Are you flying on business, or on your own money? A business traveler barely glances at the price and isn't the one paying it. Everybody else shops around. Same seat, two customers who behave nothing alike, no way to tell them apart.
They couldn't just ask. Ask a guy in a suit whether his company is covering the ticket and he'll say no, because the honest answer costs him a few hundred bucks.
So they built a fence out of your calendar. Saturday-night minimums, advance-purchase windows, rules against back-to-back ticketing. Decades of machinery, reverse-engineering something you knew when you booked.
Low-cost carriers mostly killed the rule in the early 2000s. It came back in 2008.
Every pricing team learned the same lesson: intent is something you infer, because the customer will never just tell you.
Which is true right up until it isn't.
A woman visits the same skincare store twice in one week. Monday she's out of moisturizer and wants in and out. Saturday she has ten minutes and no agenda, and might leave with a serum from a brand she'd never heard of. She gains nothing by lying about which trip she's on. Nobody asks her.
A field study published this August in the Journal of Retailing and Consumer Services went through 3,819 items on 323 grocery receipts. The ones who came to browse had 8.6 times the odds of an unplanned purchase compared with people running an errand. Nobody has run that test on an online store.
Today's idea is a Shopify app that asks one question, restock or discover, then merchandises the store around the answer and measures it against a control. Fifty beauty merchants at $99 a month is $5,000 MRR. Two hundred fifty at $199 gets you close to $50,000. One person can build it, in an app store of 17,000 listings where nobody has bothered to ask.
Read the full playbook here:
Every Shopify personalization app profiles who the shopper is. A 2026 field study says why they came matters far more. Beauty merchants can test it in a week.
From the Vault:
Signal-based selling turned job changes and website visits into a $5 billion category. Zoning permits, parcels, and demolition filings still reach nobody's CRM, and that gap is a business.
ASHRAE charges $6,580 for a newsletter placement that averages 77 clicks. A verified local list of Texas HVAC contractors is a different asset, priced by different logic.
