I think they're asking, why would you spend $20+ on a board like this when something like a Lolin S2 Mini[1] is $4? There are millions of ESP32s out there... What makes one from Arduino™ any better?
Because the difference between $20 and $4 is nothing if you're prototyping for a real product and you may prefer to have business partners in Europe.
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.
Are Aruinos really aimed at the professional prototyping market? I’ve always had the impression they are aimed at students and hobbyists. These two groups are generally more price sensitive but do also value ease of use.
For these non-professional groups, what are the benefits of a $20 Arduino ESP32 vs. one of the many $4 ones?
People use arduinos in real professional prototypes, yes. Some prototypes are held together with pieces of string inside.
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
The only two examples I can thing of are not Arduino and not prototypes (these are production units) but the Wi-Fi module for Garo EV chargers is a Raspberry Pi with an angled GPIO header.[0]
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]
It sounds like you're saying price doesn't matter while prototyping, so choose what's convenient. But what's better for prototyping? A Raspberry Pi Pico W has a better SDK and better documentation, so why not go with that? (It's also $6.)
It doesn't even have on chip wireless and the drivers are proprietary. Also external flash that can't be protected using fuses. If's fine for hobby level stuff, but that's about it. If you want to make a product and not have it cloned and the firmware copied, good luck. Also the ESP32 has a power management coprocessor allowing it to.operate on batteries, wake up and do stuff, then go to sleep.
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.
Everyone is talking specs, which might be a reason someone picks a product over another, but I'll offer another anecdote:
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.
I haven't dealt with Arduino the company, but even for two entirely identical products, there may be reasons why someone would choose one vendor over another. It really depends on the purchaser's specific priorities and requirements. A significant benefit could even be something a simple as "they have the same business hours"
1. https://a.aliexpress.com/_mspsSKa