There's not really any real tension between "you should know their stated rates are bullshit" and "they should accurately describe the service they are willing and able to provide".
One is a stupid way to run a society and the other isn't.
You're never getting 1G 100% of the time, you're getting a target of 1G and statistically if you do a speed test you probably won't be doing that at the same time as everyone else.
A little knowledge can be dangerous, that's not patronising, it's that accurately describing your network topology to all customers is hard and easy to misunderstand. Some segments of the network will be heavily contended, and others will be under utilised. Being heavily contended might be undesirable but it's pragmatically going to happen.
Where it breaks down with customers, is where the segment is over-contended to the point where they consistently can't meet the product description. But that's not a service description issue, it's an investment problem and if it's not being dealt across the board by the provider, then that provider will be crap.
The bigger issue in this case is a lack of effective competition which drives vendors to have a decent quality of service. Being more transparent won't help with an under provisioned network if you have no choice. In markets with poor competition, poor service provision and capacity usually follows.
One is a stupid way to run a society and the other isn't.