> Finally, I’d like to note that this sort of dev work goes beyond hubris. It’s dangerous. The more we assume we know without verifying, the greater the risk. In this case, the dev is risking someone else’s livelihood.

I think this is a bit of an overstatement. The dev states it’s her brother’s business, and one can assume he’s asked her to help him out.

Getting the service to be 100% perfect is of course a near impossible challenge, but that’s most likely not the business owner’s concern — they simply want a way to avoid totally losing business. If the service can convert even 10% of customers with a rough quote and timeline it’s most likely useful.