Both genders have a right to board the bus and sit on the bus.
True. But saying that people in Group X have to sit in those seats and people in Group Y have to sit in those other seats is considered segregation, and is illegal (if the groups are based on protected classes, of which gender is one). Separate menus is another area where discrimination can occur — you can’t have a a “whites only” menu and a “blacks only” menu. In other words, admission to the facility isn’t the only point where illegal discrimination can occur.
It’s no different than a restaurant saying that “[insert group here]” has to eat at the shaky tables with the wobbly legs and with the chairs that are falling apart, while [other group] can eat at the new, solid tables and comfortable chairs.”
The Wolf