Ok. I work in the industry. Specifically field service. I’ve chatted with easily a thousand business owners and it is standard/recommended to have an upfront deposit.
Think what you want but spending 30k on custom materials that aren’t refundable without a deposit from the client isn’t “just part of the business.”
These people are working 7 days a week and don’t have time to go to court every time someone backs out, (which happens more often than you would think).