I hired company to remove relatively small Yucca tree & roots from the dirt alongside this bldg. Turns out they busted (?) A galvanized pipe, & something about a "T." The quality plumber says they have to return tomorrow for a major job which now involves a jack hammer & access to the inside. Cringing as I ask for reactions?

Can't answer your question with the limited info you provided.

Generally, sub contractors are liable for damages they cause. Meaning: they have to have insurance.

Most damage to a water line in the soil outside of a residence doesn't require access to the inside. Maybe the line comes out from the crawl space and the plumber needs access to attach a new line from a fitting under the house to the outside line.

One house I opened the slap on the wall on the other side of a tub, in the living room, to get to the leaking cast iron drain pipe. Replaced a section of drain pipe, back filled the hole, compacted it and then cemented in a patch. Covered the concrete with the old padding and carpet. Problem solved.

On another home, I went in from the outside, under the foundation and to the broken toilet line, 3 feet inside of the exterior walls. I replaced the pipe and toilet flange and the back filled and cemented back in that area.