Substantially all problems were solved by someone else first. That doesn't meaningfully inhibit you from solving them, too. Reasons why this could redound to your advantage include superior marketing, positioning, ability to attack different niches, lower cost structure, or the ability to survive off the crumbs the big guys don't care about.

It's totally worth it for me to have the CEO and head of product development talk to your office manager for 30 minutes then custom code an import script, to get you onboarded at $200 to $500 a month. The 800 LB Gorilla basically doesn't care about you below $1k a month.

The crucial detail is that some small HVAC company may not even be using an "enterprise/business software product"... In fact they're probably still keeping appointments on a sheet of paper.

Very late to this party, but...

I'm used to my dentist's office manager calling me every six months to remind me about my cleaning appointment. This last time, the call was automated and I instantly thought "hey, Appointment Reminder."

No, it turns out it was SmileReminder that the dentist uses. When I went in for the appointment I spoke to the office manager and the light in her eyes was obvious: "Now I don't have to spend hours calling everyone to remind them. I love it" No idea how much they pay for the service, but it's obviously worth it to them.