It is kinda hilarious. I met with some of the people involved in making these rules (after the fact) and remember saying that I could just tell the inspector that I'm making a "summer kitchen" in the garage and will plug a stove into the 14-50, thereby negating the labeling requirements. The answer was "well, uh, yeah I guess you could do that". Your welder example would have been better, but I didn't think of that!
One of the issues that they're trying to address (and I do get this) is to figure out how to notify electric utilities of these installations. That is partly why there are all these new rules, and it is why recipients of the EV Charger grants will have their postal codes provided to the utility. Most electrical loads have some diversity to them (cycle on and off), but EV charging is a continuous draw, often for many hours. The weak link in the distribution chain is at the transformer on the street, which is historically sized taking load diversity into account. Primary feeder capacity is not generally an issue, and the service conductors coming into the home are also not an issue as they are (or should be) sized to the maximum capacity of the home's main disconnect. Utilities are really thrilled to have these new loads (they do represent revenue, after all) and would like to proactively make sure that the capacity exists to supply them. Nobody wins if distribution transformers fail. It's inconvenient for the affected customers, and costs the utility money in damaged equipment. I can utilize my smart meter network to create virtual meter points at transformers to watch for overloads, but by that time, it may be too late. Ideally, I can change that transformer in anticipation of the load and avoid failures and service interruptions.
One of my personal goals at the utility I work for is to be an advocate of EV adoption. EV's are a "behind the meter" activity which utilities are generally prohibited from getting involved in. Our demarcation point is at the meter. Entities like the ESA (responsible for behind the meter safety) are new at this too, and we need to figure much of this stuff out. I'll probably try to start with some education materials on our web site to help people understand the challenges and solutions that are available to them.
