Those would be normal "initial quality" problems for RVs, yes they are still common from many manufacturers. Shoddy workmanship is common, inadequate engineering is common, it is all about containing cost to make a profit at the price a buyer is willing to pay.
"Lemon" has a specific meaning, defined by statute in each state, and "lemon law" is about procedures to provide replacements for vehicles that cannot be fixed under warranty. The law usually what conditions constitute "not repairable" and is about unservicability, time out of service, and failure of multiple attempt to make a repair.
True "lemons" are pretty rare in the RV world, but unfortunately when a new RV turns out not to be repairable, the state's "lemon law" often doesn't apply, and you are left dealing with the manufacturer by yourself.