If you travel to Bangkok, you may chance upon signage in public transport that encourages people to give seats to the needy and monks.
How is an able bodied monk under the same category of people needing a seat? For non Buddhist, it is hard to fathom.
In Thai Buddhism, great respect is given to the monks. More importantly, respect is paid in recognition of what their monastic robe signify. When a person don the monastic robe and becomes a monk, it signify the great renunciation of daily indulgences to pursue a life of austerity. From that point onwards, the monk or nun is not encouraged to have any bonding relationship with others.
Renouncing violence for all living beings, harming not even one, you would not wish for offspring, so how a companion?
Wander alone like a rhinoceros.Khaggavisana Sutta
In Thailand, this position evolved into a social effort to avoid any physical contact with the monastic community. It is therefore out of such consideration, that the lay community, keep a respectable distance from the monks.
When associating with a monk or nun, it is customary for them to seat on the chair while the laity sit on the floor at a respectable distance. When walking, the laity will walk at a respectable distance behind. Private meetings are absolutely discouraged. Therefore always speak to the monastic community in public. (with 2 or more people present)
Such social etiquette promotes a form of dignify respect and reduces the chance for misunderstanding.
Therefore, a seat that is close to the exit allows a monk to enter and leave the public transport with minimal contact with others.
May you be well and happy.