Well that’s where I’ve been going wrong in my career. I have worked for 2 startup companies, who faked product demos, in software.
I’d come from corporate background, where it was all fairly standard off the shelf software we sold and implemented. Not above the odd white lie, but the products could do what they claimed.
In the startups, the first occasion I did a presentation on a laptop. I was new to the company, had a couple of days training. The demo went great, the client loved it. Since I would also be managing the systems integration, I asked the devs how exactly x talked to y - and they said it didn’t yet, I’d just shown a simulation. Looking back I was naive, but I quit at the end of the week . I had no idea it was not uncommon.
I think people outside tech have no idea how common place this is.