Old home renovations are expensive because of these stupid codes. You have to bring a house up to code in many cases which increases the costs. You’re right that home renovations are more costly.

For new homes it’s easier just to start “at code” and go from there. However, there are places that have strict building codes on the type of lumber you use for the roof, the frame, interior walls, exterior, etc. Lumber yards who sell this in bulk know this and charge a dozen percentages more for it.

For example, in Virginia, lumber has to be graded for use for certain applications. If you happen to mill your own boards, your SOL. You’ll never be to code. The only way is to grease an inspector.