whence comes your reference to 3 degrees ?
My 747 flight handbooks:
The types of fuels available for use have a wide range of freeze point
temperatures, generally between -38° and -58°C. When fuel with a restrictive freeze point is used, be aware of the limitation on fuel tank temperature of freeze point +3°C. If fuel temperature approaches limit, decrease altitude or divert to warmer air. Increasing Mach number will tend to increase the resultant fuel temperature obtained after extended periods of cold soak.
I believe that aircraft that use fuel icing inhibitors are typically ones that don't have oil to fuel heat exchange systems such as some bizjets.
It also depends on the place that sells the fuel. For example, if you go to Anchorage, AK, you will get Jet A50, with the -50C freezing point.
I've found that Jet A+ is more often sold outside the US.