Yes, they'll increase per-unit prices to do a longer warranty.

But that price increase will go into longer-lasting parts, because that costs a lot less than needing to replace every unit halfway through the warranty period.

And since the 20 year oven is a lot cheaper to build than two 10 year ovens, the per-year price to the consumer will go down.

How will moving production to low wage countries help? The importer and/or the retailer still have to comply with the law of the country they sell in.

The only exception is when people buy from a foreign retailer online. However that is a problem regardless of where the retailer is as long as they are not in your country. My daughter (in the UK) currently has a problem with Boox (in the EU) refusing to replace a product that was delivered with a faulty screen claiming that she must have damaged it.

I'm pretty sure that manufacturers have some room to include a 9-year reliability in the design of a +700€ oven. That's why consumer laws have differents warranties.

They're already doing that, so you may as well exercise your rights (and help the environment at the same time).