Roland,
Well, I can understand your point, but take it to it's logical conclusion - If I assume that you bought your car secondhand, did you immediately replace braking / steering / suspension systems, on the grounds that you dont know the full history of these safety related items?
More likely, you checked over these before buying to satisfy yourself of their condition.
Thats exactly what I did with my second-hand caliper, but with the added advantage of being able too peel back the boot and check the piston condition and action. If I wasn't happy with it, I wouldn't fit it.
Someone more cynical than myself might suggest comments such as yours likely come from someone with an interest in the new parts industry, and lets not forget that new parts are not immune to failure.
Safety is more dependant upon the application of intelligence and common sense than paying out for the most expensive option.
Hope you don't take my comments the wrong way, but I just cant resist a friendly argument ;-)
Cheers,
SP