Every other trade on this list sells to somebody with a problem today. A builder sells to somebody with an idea, and an idea keeps its own schedule. Financing, land, a contract on a house they haven't sold yet, a spouse who isn't convinced. Any one of those can hold the job for a season without the customer ever going cold.
Two people have to agree, and they're almost never in the same room when the form gets filled in. That means the pitch has to survive being retold badly by one of them to the other, which is why a walkthrough video of a finished build does more work here than any amount of written copy.
The volume needed is small and that misleads people into judging it wrong. A handful of jobs can be a whole year, so a month with two inquiries isn't a failure. What's a failure is the inquiry that went quiet in March and was never contacted again, and then broke ground with somebody else in September. Most builders' follow-up stops a long time before the customer's decision does.