that the two sites are vastly different in terms of purpose. On this site it is the very absence of commercial constraint that allows people to experiment and try new things... so its expected that people aren't writing songs to pass a test.
For that reason, the way a song would be evaluated on TAXI should be vastly different than the way it is evaluated here... two different sets of ears, so to speak.
On TAXI the critics look for polish and for how well it met the criteria the project was looking for.
On the User Showcase, the comments revolve more around clever use of the software, whether it make us feel good when we listen, whether the persons skills are improving, etc etc.
In a nutshell, this is an INCLUSIVE environment, while TAXI is an EXCLUSIVE environment.
IMO...(with no presumption of being a 'heavy hitter' here)
The above are very important distinctions to consider when one is looking for comments or quite honest critiques.
Responses to songs posted here (and similar sites) tend to be more about
encouragement to all song writer submissions regardless of any perceived skill level.
For the most part, critiques will be soft and cater more to the 'can't say something nice, don't say it' approach.
BUT, for the record....BOTH have their place for participation and will depend on one's musical goals and the thickness of their skin.
Personally, I've never joined TAXI or any related sites over decades of songwriting because I don't write to the masses nor do I think my material would have any possible mass appeal anyway.
Just because I've written a song that took me weeks of angst to flesh out does not necessarily equate to a masterpiece...well...maybe in my dreams.
I'd be elated just to elude the 'you totally suck' genre.

I'd guess many to most here (including me) likely write/record for their very personal creative therapy.
Best to all here with their music pursuits....one never knows what can happen should the right person hear something one has written.
That's my take on it....carry on.