Wouldn’t an experienced mechanic realize that the brake bleeding valves were at the bottom of the caliper and pointing down instead of like they should be, at the top of the caliper and pointing up? On first inspection?
I can see how a DIY’er might reverse the calipers side to side. But an experienced mechanic who’s addressing a customer complaint about air in the system and is charged with bleeding the brakes not noticing the bleeding valve is at the bottom of the caliper? Or would this problem be more difficult to observe than it seems?