That's some bad marble. Typically marble is not the most durable or hardest but some are capable to do well in a rough use kitchen. Search for more. I've been living in a family of 16 with cooks maids and help. We don't use chopping boards or anything on our marble and the kids often make huge messes and they are there for long many times. It's never left a stain. Check out other places

That demonstrates the point. I do think most people wipe up stains quicker than 8 hours, but carelessness happens. I would cry if that happened to me.

I remember an aunt who was eighty something in a home built in 1900. There was marble in every bathroom and on floors. I don't remember stains, nastiness or chips and gouges. Interesting that these are concerns now. Have finishing/polishing/household cleaners, etc... changed that much?

Smart move to test before committing!

Were the samples sealed?

Marble is a natural stone, maintenance of resealing is required. Sealing the stone helps protect it but does not make it stain proof. Your demonstration above will still stain a white, sealed, marble. Your best bet would be to go with a man made product. Caesar Stone, Silestone, etc are ideal countertops that require no maintenance. They are coming out with new looks that mimic carrara and carrara bianco marbles, very hard to tell the difference. You can also get these products in a honed finish. I would call a local fabricator to see what they would have to offer.