Many companies easily drop a $10,000+ premium for a prototyping kit every day of the week to get support from a preferred vendor. If you give one employee making 150k/yr a 10% productivity boost, you're saving money. Prototyping cost is often mostly labor. Unit cost doesn't really matter as much until you're talking about the production BOM.
Some rough math, for an employee with a 200k fully loaded cost working 1800/hr/yr, the difference in the price of those boards is about 8-9 minutes of labor. So if it's 10 minutes quicker to get the documentation for the Arduino -- it's cheaper.
So I might well start developing on an ESP32 board knowing that my final target is an ESP32 custom board.
The RP2040's highlight is the PIO and the ease of deployong the firmware, although I find flashing the ESP chips much more straightforward.
Anyway, there are still issues with the official 1.20 and 1.19 micropython esp32 spiram images throwing random guru meditation error messages from esp-idf. I'm using it them with several ESP32 WROVER modules, they all crash in the same ways. Maybe I waste 19€ plus shipping on a Nano ESP32 to see if it still crashes on the U-blox module.
The last time I bought some prototyping gear, there were a half-dozen options that met my technical criteria. The option we ended up choosing was the first place to answer the phone, discuss our specific needs, and give us a delivery date.
There's a lot of good prototyping boards out there, I'd bet a lot of buyers are making decisions based on how quickly they can get back to business, rather than taking a fine-tooth comb to a spec sheet.
For these non-professional groups, what are the benefits of a $20 Arduino ESP32 vs. one of the many $4 ones?
Also, the Wi-Fi module for Ebeco floor heating thermostats is a custom PCB with a SMD mounted ESP32 board. They never show that side of the PCB in the photos online but I have one and that's what it is.[1]
[0]: https://www.garo.se/sv/proffs/produkter/e-mobility/tillbehor...
[1]: https://www.ebeco.com/products/accessories/eb-connect-wifi
You use Arduino for their super good support and documentation while you're building your device. It's only for prototypes.
You can buy $4 boards off Aliexpress, but then you have to deal with poor documentation, clone boards, buggy code, etc.
I lost 4 days trying to make an SPI screen just "work", until I realized my clone board was outputting the signals offset due to a hardware bug.
I'm not sure why it'd be particularly surprising? Their whole thing is being easy to use and quick to iterate with.
Edit: if you want an example industry, the one I can remember is a bean to cup coffee machine. I guess having multiple small systems that need controlling in consumer appliances is a good fit for something like an Arduino
For professional prototyping I always buy Arduino, for home use the cheaper variants are fine too.