As Ray hints at in his reply, Most European caravan manufacturers use many of the same suppliers as the UK for OEM equipment.
Having worked 20 years before retiring in 2000 for a supplier of OEM equipment in the UK, I was in a position to make an informed assessment of the faults on our appliances.
It must be noted that of the total annual tourer sales continental marques represent a very small (but growing) percentage of sales. It is usually dangerous to make generalised comparative statement with such a disparity of sample sizes, but in this instance there were traits that may be tell a story.
When surveying all reported faults (UK & Continental)there were three generalised headings they could fall under:

Appliance not working,

hmy: Parts missing from appliance,
:S Damaged appliance.
With UK caravans the spread of reports covered all three categories, but continental caravans are heavily biased to the just the "appliance not working"
After investigation the underlying reasons were hopefully exposed, and they could be categorised as:

Appliance complete, installed correctly but defective.

Customer using wrong operating procedure.

hmy: Appliance installed incorrectly preventing it from working

Appliance incomplete allowing partial or no operation
:S Appliance damaged.
:evil: Incorrect appliance fitted.
Again for the UK built caravans there was a broad spread across the categories, but for continental there is a strong bias to the top two categories.
Our company was at the forefront of appliance manufacturing processes and we were satisfied that product leaving our factory had been fully tested for operation and safety. We were alarmed at the numbers of our appliance being returned by manufacturers and when they reached the final customer. We identified that in many cases the problems with our appliances were being created by the installation by the manufacturer.
so we set about trying to identify the reasons. This involved visiting all the UK manufacturers and to look at their product handling and installation processes.
We worked with the caravan manufacturers to introduce protective palettes so that storage and handling can be managed in easy product quantities.
We split the appliance engines from the cosmetic parts so they could be moved in bulk to be assemble at different part of the their productions lines.
Despite these and other innovations we still received damaged product back from the manufacturers with them claiming they were "faulty" - yes becasue some pallets had been skewered by a lift truck blades, and others were full of water becasue they'd been left outside in the rain! Products had parts removed from them, others had foot prints and dents. Other were filled with products from other OEM manufacturers!
It's all down to Quality Control at the caravan manufacturers, or more to the point lack of it. We supplied quality assured products, and they just didn't look after them. Admittedly this was twenty odd years ago, but the same issues still seem to arise, so I wonder if anything has really changed that much.
There were bad and better manufacturers here in the UK and I'm sure the same applies to the Continent, but on the basis of what I saw back then, I'd have greater confidence in some of the Continental caravan manufacturers products.