A second sim is the only options for some. Either ChatGPT or one of those requires a real-world mobile number. Anything on a VoIP is blacklisted. I literally can’t sign up for it or a couple other oddball services (like the Dunkin’ app*) because I refuse to divulge my carrier number to anyone but my family and 2-3 close friends. I have a (former) mobile number and two former landline numbers on VoIP that are my real, active numbers but some services simply refuse to use them.
* I’d use my freebie backup sim for registration, but many use that # as their required+sole 2FA “security“ so signing up with it is useless as I’d have to use that phone every time I interacted. Maybe it’s time to look into eSIMs.
Your passport contains biometric data (your photo - not as complete as a depth scan or multi-spectral image, but still biometric).
There are two (well, threeish, legitimate) reasons for biometric. First, it is currently harder to fake. Digital passports are difficult but not impossible and non-digital are relatively easy, especially for state actors. Second people are stupid (or unlucky) and lose their passports, which leads to a shit-ton of paperwork to fix. Third, and this is really the rule for which lost docs are a sub-problem, efficiency. Even the cheapest front-line human costs about $100 an hour, including management, training, benefits, etc and I’ve yet to meet an international (or domestic) traveler who enjoys waiting in hour+ lines to get through passport control. Less contact time / zero friction interfaces are both better for passenger attitude and cost efficiency.
Until we stop the practice of drawing imaginary lines on the planet and regulating which side each person is allowed to be on, nearly every travelers and pretty much all the boarder control apparatus is going to want to spend as little time and money on one another as possible.
From a practical perspective? They could eventually cross reference the exits to arrivals, automatically flagging those who have overstated their visa (or, more specifically, automatically clearing those who have left). The data (exit data) is generally useful for all sorts of mundane statistical work. From an automation standpoint it’s both cost effective and time saving. Anyone who’s queued up in an hour+ line to get through border patrol will attest that the prices can be infuriatingly slow.
Of course, that the data can be used for non-official or privacy-adverse uses doesn’t make the collection ok, but that fact also doesn’t mean that the data isn’t useful for its overly intended purpose (automated tracking of everyone who leaves)
That’s an urban legend. Prices are aggregated and cataloged by ITA matrix (purchased by google/alphabet a decade ago). The only time a price change is when the airline itself changes the current retail price.
Now, if you’re using a third party service - like Priceline or Travelocity - to check and book tickets (which is a terrible idea, btw) they may track your history and alter their price, but the master index (served by google flights from ITA matrix) will not change for you, personally, or your specific ip or other identifier.
Note: Airlines will adjust their prices based on interest/purchases, so if you’re hitting a flight with requests to bill so hard that the airline thinks the flight is popular, or you go through the reservation process far enough to “fill” a particular fare class, then the price will change - but it will change for everyone, not just you. Similarly, Amazon will raise pricing during a buying surge - but it’s for everyone, not just you.
On the (mostly) plus side for untracked browsing - as long as it’s so tight that you’re hopping ips and avoiding any back end fingerprinting of your system - Many merchants do source-based pricing. Ex: if you go to book certain services direct vs following a referral link (like via a cash back site or association) you my find different pricing. Using and AARP link to some travel services will result in a 25-30% price increase, to offset the 20% rate coupon they offer, plus a little coin for themselves. Other sites will also trigger cost basis alterations - especially for services which are hard to identify or compare a fixed cost.