When someone tells you about the amount of people try asking them..."how much people"
The result is usually an immediate response of, "do you mean how many" to which you can reply "no, i mean how much" and every time I've tried this the other person has said "well, that's bad grammar."
You can then point out that the grammatical error is their's and continue to talk about the use of ;
for free when you mean free
males and females when you mean men and women or boys and girls
warm or cold temperatures
myself when you mean me
going forward when you mean in future
and the popularity at the moment of doubling up by saying
reverse back/repeated again/ and countless other examples which you can never recall when you need to list them. The problem is that once you're aware of these annoying things you hear them constantly. Life can be tough if you care about the language.