FranklyYou are usually buying underlayment
Clay tile can last far longer than the waterproof membrane beneath it. When a tile roof starts leaking, the honest scope is typically lift the tile, replace the underlayment, re-lay the tile — not buy a roof's worth of new clay.
Historic and matched tile
On older LA homes, the existing tile may be difficult or impossible to match. That is a strong argument for reusing it, and a strong reason to ask what breakage rate the contractor expects and how replacements will be sourced.
Ask for both prices
Lift-and-relay versus all-new tile, side by side, in writing. If the contractor will only quote the expensive option, ask them to state in writing why the existing tile cannot be reused.
Cracked tile is not always age
Damage clustered along a walking path to equipment usually means foot traffic. Scattered breakage across the field is a different story. The photos should let you tell which one you have.