Main idea

In Brazil, the CPF — the unique tax ID number assigned to individuals — is asked for at the register for ordinary purchases, including a simple coffee. Refusing, or not having one, takes the cashier aback.

What matters here isn't the legal rule, it is what its banality installs: the most everyday transaction is attachable to a unique identifier, and nobody finds that remarkable. Mechanisms like the CPF on the receipt link the identifier to the sales slip and give it a tax-incentive logic; the cultural effect goes beyond the mechanism.

Seen from France, where the debate on personal data turns on principles, the norm looks inverted. It isn't: it is elsewhere. It's not that privacy matters less, it's that the practical infrastructure of everyday life has placed identification at another point in the chain.

Why it matters

For a product that collects, the same field changes status from country to country: asking for a national identifier at sign-up is a major friction in one market and self-evident in another. The consent cursor doesn't copy from one country to the next.

And it invalidates the most common design argument — "our users will never give us that" — when it is transposed without being re-checked locally.

Nuances and limits

Not every request for an identifier has the same status: some stem from a legal obligation, others from a tax-incentive mechanism, others from commercial habit. Conflating them leads you to believe in a single rule where there are several regimes.

And a normalized practice is not an endorsement: the habit of being identified says nothing about what people think of it.

Open questions

• Before designing a form, how do you measure where the acceptance threshold for a national identifier sits in a given country?