Assalamualaikum ustaz. My friend works as an express bus driver from the south to the north between Malacca and Penang every day. Is it permissible for him to perform the jamak and qasar prayers daily?
Waalaikumussalam wrt. wbt.,
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions, and all those who follow his footsteps until the Final day.
Jamak and qasar prayer is a rukhsah (facilitation) given by Allah SWT. It is a facilitation granted to the Muslim ummah so that they are able to pray where ever they are. This is stated by Allah SWT in His statement:
وَإِذَا ضَرَبْتُمْ فِى ٱلْأَرْضِ فَلَيْسَ عَلَيْكُمْ جُنَاحٌ أَن تَقْصُرُوا۟ مِنَ ٱلصَّلَوٰةِ
“And when you travel throughout the land, there is no blame upon you for shortening the prayer,” 
In answering the above question, first and foremost we’d like to congratulate you and alhamdulillah for your concern about the obligation of performing the obligatory prayers by the questioner’s friend. Nowadays, many were negligent in their prayers, too busy seeking the rewards of this temporary world. Furthermore, there are some bus drivers who disrespect the rights of their passengers to pray by refusing to stop at any mosque or R&Rs.
It is permissible for a daily traveller due to his work to perform jamak and qasar the ruba’iyyah prayer (four rakaat prayers). The reason is the illah for the permissibility of jamak and qaasr prayer in madhhab al-Syafie is a long journey of 2 marhalah (82 kilometres) or more. This is different from madhhab Abu Hanifah which conditioned the permissibility of qasar for a journey of more than 3 days and not based on the distance.
However, it is prioritized for a traveller who travels for less than 3 days to take the azimah (original heavier ruling) and not the rukhsah, as a way to avoid the khilaf. 
In our opinion, one should also consider the aspect of the trouble of finding a suitable place to pray, water supply and the time constraints as the reason to take the rukhsah of jamak and qasar.
May Allah SWT grant us all the strength to worship Him.
 Surah al-Nisa’: 101
 Narrated by Ibn Hibban (2739)
 See al-Fiqh al-Manhaji, 1/190
 See al-Mu`tamad fi al-Fiqh al-Syafie, 1/464-466