Strings with interpolation look different in ES6. They don't just look like string literals. You can easily see where the variable substitutions happen.

Also, I don't know what your argument about PHP is all about. I don't agree with the idea that string interpolation is going to lead to people writing code vulnerable to SQL injection, for example. You can just as easily write "select * from foo where name=\"" + name + "\"" as `select * from foo where name="${name}"`.