By chance the name of the company doing the work isn't Crack Heads Plumbing
For starters --- it would have been more logical to tie in as close to the city main as possible -- eliminating as much as the old line as possible ( high lighted in red --- toward the back gate )
Second -- run the 4 inch toward the back corner of the garage --- bring the 2 inch into garage and tie into the 4 inch. ( highlighted in yellow )
Seems to me there was way more work , mess , material, and extra expense necessary to do the job --- not to mention the additional expense and work for landscaping.
As Gizmo mentioned -- potential issues from blockages down the road. All changes in direction to the main drain are potential blockage points. Considering the maze of piping , angle fittings , the run , will negatively impact the flow of waste in a gravity drain system.
A long , long time ago when I first started out in the trades one of the first lessons learned was the K.I.S.S rule ( Keep It Simple Stupid ) --- it sure doesn't look like this was kept simple.
One good thing though --- at least the inside of the home didn't need to be gutted.
2 cents worth.