We are surprised about your review.
We give the information about the ticket fees already in advance and mention that food and drinks are not included.
It seems to us also that you are not familiar with calculations in business. A full day van tour up to only 8 people (also amost private-tour style) with pick-up from the accommodation starting already before and with professional chauffeur guide (at least him you appreciated as knowledgeable) is definitely not overrated.
Maybe an interesting experiment to think through: Your employer sends you to somewhere for 8h (plus pick-up round before) and out of these working hours you need to wait for your clients because they visit a place which to go with them would on the one hand not make sense and on the other hand almost all appreciate to having time on their own i.e. at 5Fingers: Would you allow your employer to reduce 3h from your working time and your salary? Even though you needed to use the time i.e. for again cleaning the van because some clients did not treat it well? And because you need to leave Hallstatt and get back due to regulations there (for all that time is needed)? And also despite your right of rest time? We hardly can imagine that.
At least here in Europe we have employee rights (luckily).
We also hope people who will follow your "advise" to rent a car will not experience what can happen at locations like Hallstatt. One might be not amused to beeing sent away without even getting the chance to park the car, with no slots reserved etc. (Of course, that would have the benefit of no need for entrance fees, food and water to spend at Hallstatt but the expected sightseeing day would have been gone without Hallstatt.)
We hope these explanations helped to get a different and extended understanding.