the.com/platform ticket

means A cheap ticket that let you onto the railway platform to see someone off or meet them, without buying passage on any train.

from A fixture of railway culture from the era when stations were fenced and guarded and only ticket-holders could pass the barrier — so anyone wanting to wave off a departing relative, carry their bags to the carriage, or simply loiter and watch the trains had to buy admission to the platform itself, like a ticket to a stage rather than a journey. Common across British and other rail networks for much of the 20th century, platform tickets faded as stations relaxed their barriers and open access became the norm, leaving the phrase as a small monument to a time when even saying goodbye cost a fare.