I explained it a couple other times in the thread chain, but most European countries still use cold most of the time. Most places in Europe (like France) have 230v 50hz electricity. The US uses dishwashers on our 120v 60hz system (we have a 240v 40 amp system for our main water heaters). While the 120v system works great for most things, it does a pretty terrible job at using resistance heating for warming up water.

So plumbing cold water to the dishwasher in the US would make it take a lot longer to get the water hot compared to you guys on the 230v system, and running the hot water till it's warm let's the water be fully hot from the moment it goes into the dishwasher, so the pre wash cycle does a better job.