is a common repair cheaper on an american car rather than japanese or german

Depends on what repair needs to be made plus what make, year and model vehicle for there are few similarities between different manufacturers and repair techniques!.. Kinda like that Apples to Oranges thing.... You'll find an Estimator at the top of this page so you can research that...

Yeah it is. Specifically because of the cost to ship parts overseas that are not made here in the US