A lot of home inspectors seem to jump to the conclusion that, just because there is a mature tree on the property, that it’s a reason to scope the drains and be sure that there are no issues.

I don’t agree.

Why fix what isn’t broken?

If you’re feeling perfectly healthy, do you ask your doctor to order you a full body scan, extensive blood work, or radiographs? No.

It’s expensive.

There are risks inherent with scoping. You could damage the existing drain, costing you a lot more.  If there’s a issue with your main building drain, then consider it.  But exhaust your cheaper options first.