Legal aspects aside, it also isn't exactly a vote of confidence in the quality of the product. I mean, 30 days, really?
1: https://europa.eu/youreurope/business/dealing-with-customers...
Some shops have down to 1 week of warranty, some (e.g. wholesale items) may state to accept no returns, etc.
No. While in the US people seem to be able to get away with anything as long as there is a disclaimer, EU law is strict - it's minimum 24 months per Art. 17 EU directive 1999/44/EC (https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CEL...), with an exception for second-hand goods (Art. 16 of said directive, with the decision on the exact duration being left to the member states).
B2B transactions, however, are pretty much unregulated wild west.