Well, I guess we just disagree. I think if you look back over the last 500 years, modern society is changing faster – technologically and culturally. Society is undergoing massive shifts more frequently, with the move from agrarian societies to the industrial revolution to the information age to the coming, IMO, biotech revolution. Or to use the classic example, I think if you plucked an adult from 1500 and transported them to 1600, they'd be able to understand and navigate society much better than someone plucked from 1915 transported to 2015.
Related to your point though is the idea that change is not just happening faster, IMO, it's spreading more uniformly due to globalization, e.g., cellphones have spread to all but the most impoverished, over 90% of the global population at the last estimate I saw.
And yes, I'm aware of Rachel Laudan, though I haven't seen The Search for General Tso. "More authentic" is clearly vague, context-dependent, and ever changing, akin to "proper grammar". You can intellectualize it forever, which can be fun, but eventually you should try actually tasting the food. You will taste the difference in a bagel made from traditional ingredients, i.e., no fats. You can rightly argue about exactly what is meant by "traditional," but at some point, there's a way that's been practiced for hundreds of years and there's a newer, more automated way.
That's not to say I'm right or that the factory-produced food is always worse. I know many people who think Panera has fantastic bagels. I disagree and think they're far too spongey. But there is a difference.