There are no faregates in Vienna. Tickets can be valided when you enter the transit system, and it’s still an open barrier free system. There are inspectors in the transit system who can ask for passengers to provide proof of payment. This is of course how the entrances to transit stations once worked in Vancouver, prior to the introduction of faregates.
How has the transition to faregates worked out for Translink? How much did it cost in the end and was it worth it? Were any big savings realized (fewer or no transit police, no ticket inspectors, etc.)? Is it worth the extra hassle to have barriers? How can other cities around the world keep their transit systems open and work on an honour system?
https://www.wien.info/en/livable-vienna/smart-city-vienna/most-liveable-city-economist-352350
https://www.economist.com/graphic-detail/2023/07/25/these-are-the-most-liveable-cities-in-europe
CityHallWatch: Tools to engage in Vancouver city decisions 
The fare-gate issue was pure politics, where friends of the Gordon Campbell Liberal government got the contract to sell a largely obsolete fare gate system. In today’s transit world, fare-gates are obsolete.
The U-Pass, with over 120 thousand issued has made the fare-gate in Vancouver redundant. The concept of a $1 a day universal transit use has made the concept of fare dodging obsolete.
Over $1 B was wasted on bad fare gates and Compass Card. We will all need a new Compass Card by 2026 .
The present Compass Card is first generation and does not have features that exist at other progressive transit systems. Like fare capping or pay by distance instead of our unfair fare structure with unfair 3 zones.
https://dailyhive.com/vancouver/translink-distance-based-fares-june-2018
Maybe the author and commenters have some knowledge of transit systems but it doesn’t show here. Both New York and London transit systems, that I have personally used recently, have faregate systems. Clearly they don’t think it is “obsolete”.
Many Transit Systems have turnstiles which are way better than TransLink fare gates which many riders can get through.