Revert change that made fare_rules.txt conditionally required.

[bdferris-v2]

When the initial Fares v2 base implementation was added to the official spec (#286), it also included some changes for Fares v1. Specifically, fare_rules.txt was now marked as conditionally required if fare_attributes.txt is present. I believe this change was a mistake and should be reverted.

It's my understanding that fare_attributes.txt has always been allowed with a single entry to indicate a flat fare for all rides. In this scenario, fare_rules.txt is not required. This behavior was documented on the original Fare Examples wiki entry and has been (described elsewhere)[https://docs.google.com/document/d/1mK3--o5g4-3cCXaqmch92U63JTwChh0L2VCmcDViIlM/edit#heading=h.1xji1nf0ko4z] as well. More importantly, I count ~40 feeds in the MobilityDatabase that are currently relying on this behavior.

There was also a comment from @flocsy calling out this behavior in the original PR discussion (#286 (comment)), but I think it got dropped in the lengthy Fares v2 discussion?

Given all that evidence, my proposal is to revert the language change making fare_rules.txt conditionally required.

See also the related discussion in the #gtfs-fares slack channel and related discussion for the gtfs-validator.

gtfs-changes announcement: https://groups.google.com/g/gtfs-changes/c/Jn8OIuK6J54/m/RWg9hqwTBQAJ

[flocsy]

+1

[isabelle-dr]

Thank you for opening this @bdferris-v2
I confirm the intention for this change was to describe the relationship between Fares v1 and Fares v2 files, and not make data with only fare_attributes.txt invalid.
I think the example section of gtfs.org provide a good explanation of this relationship.

[bdferris-v2]

This pull request has been open for more than one week, so I am calling for a vote. Note that this is for the proposal to revert change that made fare_rules.txt conditionally required.

Please vote with a +1 (for) or -1 (against) in the comments. Voting ends on 2022-12-07 at 23:59:59 UTC.

[skinkie]

Brian knows best +1 (OpenGeo)

[SteveGladstone]

+1 Maryland Transit Administration

[bdferris-v2]

@flocsy any chance you could chime in with an official vote here?

[flocsy]

+2 :)
not that it matters, 'cause so long everyone who voted voted for it it'll pass, even if it's just 1 vote IMHO

[isabelle-dr]

We need at least three (in addition to having no -1), thank you @flocsy :)

[bdferris-v2]

The voting period has passed and the proposal received three +1 votes and no -1 votes. I believe that meets the bar for acceptance. Thanks everyone!