You are right, QR codes are very easy to decode if you have them raw, even the C64 should do it in a few seconds, maybe a minute for one of those 22 giant ones. The hard part is image processing when decoding a camera picture - and that can be done on the C64 too if it has enough time and some external memory (or disks for virtual memory). People have even emulated a 32-bit RISC processor on the poor thing, and made it boot Linux.

In almost all microwaves, the control circuitry or mechanical switches only ever switch 2-3 power circuits: motor+fan(+bulb sometimes separately) and the heating (transformer+diode+capacitor+magnetron) high voltage circuit. It can therefore only switch the heat between 0 and max, usually in a slow (15-30s period) PWM cycle (that hopefully does not coincide with the tray rotation period). The inputs can be manual only, or sometimes there is also a scale, moisture sensor and microphone, along with thermal fuses for safety.

I think the pizza setting is just generic medium one with short 50% cycles to allow the heat to spread. The popcorn setting can be much more interesting:
https://www.youtube.com/watch?v=Limpr1L8Pss

If it’s a joke, the website is way too committed to the bit. They appear to also have less ridiculous articles with no obvious signs of satire, host Sunday and Friday service, sell books etc. The “New Month” is probably just something to fill their WordPress template’s calendar widget that they never figured out how to delete.

• Do you think developers have any say in this?
• They have Reddit Premium for free, and most likely an internal version too.

I am not aware of any receipt printers using lasers - thermal printers have an array of resistors that get hot when necessary. I know how a laser printer works and it is hard to explain in 12 or so words. Inkjets are way easier, you can just say “squirt squirt oops”. Anyway…

1. A photosensitive drum gets a negative electrostatic charge.
2. A laser shining through a rotating prism scans lines across the drum’s surface. This removes charge from parts of the drum that should not be covered in toner.
3. A high-voltage corona wire inside the toner reservoir charges an amount of toner positively.
4. The charged drum rotates past the corona wire, getting covered in toner where its negative charge remains.
5. Paper is pushed against the drum and the powdery toner is transferred to it.
6. The paper continues into a fuser, a little oven where a heating element briefly makes the toner so hot that it melts, its powder particles making a permanent bond among themselves and with the paper. (The heater is usually stationary and heats the paper from below. The fuser drum that pushes paper against the heater can get sticky and pick up some of the toner, making images repeat down the page. This is the most common failure mode that cannot be resolved through regular maintenance such as replacing the toner cartridge and printing cleaning pages. However, almost all laser printers have a cheap fuser module or its drum available so it is usually worth replacing.)

Laser printers more accurately “bake paper so that number powder sticks to it”