Taxis wont pick you up.
Ok, how exactly does a taxi driver look at you standing on the street and tell that you speak English instead of French? It's not like French people look significantly different from other white people (assuming you're white of course). (If you're not white, that's just plain ol' racism, not discrimination against non-French people. And it's not like all French speakers are white anyway; there's whole countries in Africa full of French speakers, plus lots of African-descent people in France.)
And why wouldn't you just learn French anyway?
Quebec is the only way for an English white person to get an idea what life was like for African Americans in the time immediately after emancipation.
It was like that for AAs all the way until the 1960s, and beyond in some places.
But you're still not making sense. How do people tell at a distance that you're a white native English speaker instead of a white native French speaker? French people do not look remarkably different from people of British or German ancestry, at least not enough to tell at a distance.