Most if not all phones have the ability to dial emergency numbers without unlocking them. How many false-positives will this physical "emergency button" result

Most if not all phones have the ability to dial emergency numbers without unlocking them. How many false-positives will this physical "emergency button" result in? I'd much rather see the market address these concerns without being coerced into doing so. If consumers want a big "emergency" button on their phone, by all means offer a product with one, but forcing said "feature" on every single person who purchases a phone should be frowned upon.