[Ben73]

If we think trained professionals with flashing lights and the ability to have lanes shut down if they feel the need, need a 40kmh speed limit then perhaps we should have a 40km/h speed limit every time someone stops on the side of a highway. or 25 just so we are all extra safe.
Someone who gets a flat tyre or breaks down most likely has no training in road safety, so we should slow to 40 past them. They have no flashing red and blues or emergency vehicles to park off-set behind them to protect them while they change a tyre, so therefore we need to slow traffic.
I have heard of more people being killed while changing a tyre than emergency service workers being hit by traffic.

People will say "how often do you get a flat or breakdown"
Yeah not often, but it happens to hundreds of people around the country everyday. We should all slow, even if it only saves one life.