Does the principle that "reward is commensurate with hardship" mean that one who fasts in a hot region like Saudi Arabia receives a greater reward than one who fasts in a cold region like Canada?

Worship is not intended for hardship itself, but if hardship is encountered, the reward is greater. This is indicated by the words of Allah the Almighty: (Eat and drink in satisfaction for what you put forth in the days past.) [Al-Haqqah: 24]. Examples include performing night prayers in the last third of the night, performing Wudu (ablution) thoroughly despite difficulties, charity from one who has little, and speaking a word of truth to an unjust ruler. However, intending hardship for its own sake is forbidden by Sharia, as in the story of Abu Isra'il, who vowed to stand in the sun, neither sitting nor seeking shade nor speaking. The Prophet (peace be upon him) commanded him to speak, seek shade, sit, and complete his fast.