Smart glasses that erase everyone around you would delete the only reason working in a park works at all. Psychologists have known this since 1898. Norman Triplett noticed cyclists rode faster against other riders than against the clock, then proved it in a lab with kids winding fishing reels. The mere presence of other people makes you perform better at simple tasks. They don't have to talk to you. They don't even have to watch. This is the real product a café or a park sells a laptop…