In many settings where it is unlikely that everyone will know everyone else, badges are used so that the absence of a badge signals someone who probably doesn't belong. This is why you're typically required to wear them in a visible place i.e. on a shirt pocket, lanyard, or on your waist.

Smartphone NFC is also orders of magnitude more complex and fragile compared to traditional RFID tokens for opening doors. Saying that NFC would "suffice" is nonsensical given that blank RFID-enabled badges run approximately $3 when you're buying in bulk.

NFC requires that everyone who uses the system (incl. cleaning staff, contractors, etc) has a compatible smartphone. It is braindead stupid to assume that all of the people who need to open doors in your building:

1) own smartphones which are 2) not iPhones 3) always charged 4) not experiencing a glitch 5) never left on a desk or in a bag

Keyfobs are a common alternative to badges and similarly cheap. Because they are extremely simple single-purposes devices, they are, like badges, many times more reliable than smartphones as access tokens.

However, most large corporations are going to use badges because 1) no need for separate name tags, 2) quick and easy visual indication of who belongs and who doesn't, and 3) you're not as likely to take it off and leave it somewhere where it could get stolen or you might not have it when needed compared to keys or a phone.

You can always ask someone for their badge (either to see it, to verify they work there, or to scan it to ensure it's valid). I'd feel lots more uncomfortable asking someone for their phone.

I've challenged plenty of people trying to tailgate (either on me, or someone ahead of me). I was not shy about calling people on the fact they weren't displaying a badge; we had leaks where I was working, and it wasn't much fun.

Most people took it well. Of the ones who didn't, all but one were non-employees trying to sneak in.

> Won't NFC on a phone suffice?

Cost. Now everyone who needs badge access _also_ must have a smart phone.

I guess you could make it a condition of employment, then you'll probably pay each employee a stipend to have a phone and that's probably more expensive per employee than a badge.

And you'll run into guys like me who really don't _want_ to carry a phone 24x7 and get surly when we're told 'it's a condition of employment'.

Not everyone has a phone, or a phone supporting NFC. (Microsoft employs >100,000 people) Badges are a low cost solution which don't require charging and can be easily issued or replaced. Additionally, badges display pictures, so people wandering around the office can be visually checked by security. (No need to scan their badge)

Badges convey a lot more info once you are already in the building, such as "I'm allowed to be here" or "I'm allowed to be in this sensitive area" or "I'm allowed to be here without an escort"

In a medical setting they are very important. They convey the person's title (RN, LPN, DR, Janitor) and name. That way the janitor doesn't try to pass themselves off as a doctor and offer you medical treatment. Same as why patients wear their name on their wrist, in case charts get mixed up the medical staff checks the patient's name before giving medical treatment, the patient can't be trusted to verify their name. They could be drugged, senile, or otherwise confused or just not listening. I've learned from food service people will say "yes" to just about any question without actually listening to you. "Did you order the such and such?" "yes" brings them the such and such "this isn't what I ordered."

The beauty of a badge is that you can meet someone, forget their name when they tell you, and by looking at the badge (assuming they have it properly displayed), not have to be embarrassed that you've forgotten their name. It also serves a security purpose, but that's secondary to the identification purpose.

That would make ensuring my phone has a charge before leaving for work in the morning all that more annoyingly important.