She's right - you know I probably wouldn't recognise her on the tube, as I wouldn't believe she'd use it. But in Metro's 60 Second Interview Alicia Silverstone says "I've been taking the Underground everywhere and it brings back fond memories"
"Do people not recognise you?" Asks Metro
"I think people are so shocked that an actor would take the Tube that they just think you're a lookalike"
BTW Miss Match (TV drama that she's in) is actually pretty good and I've watched a couple of episodes on Living TV, so I do know what she looks like.