Most phones can write nfc tags without any extra hardware (& rfid with the right hardware), I have a roll of blank unprogrammed nfc tags on a roll like sticky labels left over from a job that I needed them for minus a few, some used in testing and the others on the task in hand. They dont hold much data, but its enough space to write a identifier on a tag which is all you need.
Interesting is how many software developers trust implicitly the value on a nfc/rfid tag like its set in stone and immeutable, and it opens up a new vectors into systems. And chaos if you are that way inclined.
To the op, the (implant) animal rfid chips use a different (lower) frequency 120–150 kHz which is classed as LF, so it could see something that absorbed power from the reader but not trigger it most likely as regular asset tracking rfid tags are usually much higher frequency any backscatter transmission would be on a higher frequency, this is so the protocol works when its embedded into a animals skin/fat. Theyre covered under iso 11784 & 11785 which is kind of interesting if your into the gritty details. At one point I was going to chip myself with one under the skin on one hand cyberpunk style so I could log into devices, start my bike etc using a reader, and got syringes from ireland which arrived with a sheet of paper to register myself on their pet database, but there's no security stopping someone cloning them apart from the avd friendchips ones, and the encryption schema in those was so poorly designed its broken already, and once your tagged its not just you that can read it. I eventually used the chips on my cats, because we have a cat flap with a reader and registers if a particular cat is in or out, and doesnt allow access to visiting cats. Yes I'm most definitely tracking the little furry sods
I dont know the specifics of the the cow/livestock tags that go on the ears if you meant these but irrc they are just regular rfid tags. But as theres a myriad of different standards/frequencies, its likely the same issue.
Interesting is how many software developers trust implicitly the value on a nfc/rfid tag like its set in stone and immeutable, and it opens up a new vectors into systems. And chaos if you are that way inclined.
To the op, the (implant) animal rfid chips use a different (lower) frequency 120–150 kHz which is classed as LF, so it could see something that absorbed power from the reader but not trigger it most likely as regular asset tracking rfid tags are usually much higher frequency any backscatter transmission would be on a higher frequency, this is so the protocol works when its embedded into a animals skin/fat. Theyre covered under iso 11784 & 11785 which is kind of interesting if your into the gritty details. At one point I was going to chip myself with one under the skin on one hand cyberpunk style so I could log into devices, start my bike etc using a reader, and got syringes from ireland which arrived with a sheet of paper to register myself on their pet database, but there's no security stopping someone cloning them apart from the avd friendchips ones, and the encryption schema in those was so poorly designed its broken already, and once your tagged its not just you that can read it. I eventually used the chips on my cats, because we have a cat flap with a reader and registers if a particular cat is in or out, and doesnt allow access to visiting cats. Yes I'm most definitely tracking the little furry sods

I dont know the specifics of the the cow/livestock tags that go on the ears if you meant these but irrc they are just regular rfid tags. But as theres a myriad of different standards/frequencies, its likely the same issue.
It's a passive tag which means it can't transmit its location or data, instead it responds to a reader, which could be a handheld device or these security gates that you walk through when you leave the shops.
Anything with a single-use tag, like your trainers, at the checkout should be waved across the scanner so that it is registered as "sold", which stops the security gates having a fit when you walk past.
Multi-use tags look and operate exactly the same, except they are housed in a reusable container like the pin-tags on clothes and the stopper-locks on the top of high end bottles of booze.
RFID and NFC (Near Field Communications) are very similar technologies and sometimes people intentionally or unintentionally mix the terms up. NFC, as the name suggests, tend to only work up to a range of a few centimetres - a common use is keycards for door entry.
Most modern phones can read NFC devices (Apple Pay and Google Pay use NFC), and you can get a bluetooth or USB RFID reader for them / PCs as well.