Car battery capacity in colder countries
"The capacity of the battery is affected when the temperature drops"

That is incorrect, it is not the capacity (amount of energy stored) that gets lower at lower temperatures. It is the internal resistance of the battery which increases and this lowers the current capability of the lead-acid battery. So you will be able to draw less current (and power) from the battery at low temperatures. The amount of energy stored does not change.

If a lead-acid car battery is in good condition it will still be able to start a car even under cold conditions. A workaround could also be to turn on the lights of the car before starting, now a current will flow warming up the battery and increasing it's current capability. Of course you should only do this when you are sure that the battery has enough stored energy.