Having public transport is one of those tiny details that make cities feel like they actually exist. Whether GTA 6 commits to a working system remains to be seen.

What GTA games have done before

GTA 4 featured taxis that you could hail, ride and pay for. GTA V included a metro, but it was mostly decoration. RDR2 had stagecoaches and trains that were actual systems.

GTA 6 has a contemporary city - buses, possibly trams in tourist areas, taxi/ride-hailing services. Do they drive real routes, or are they just props?