While this overprovisioning can be the case with any plans under 1gbit, If your ethernet card in your computer is only connected at 1gbit, then it can’t go any faster than 940mbit/s. If your gateway and PC both support & connect at 2.5gbit or higher, and your ISP has the uplink connected to higher than gig all the way through their plant, then maybe you could get more. Likely they are saving their multi gig switch ports for people paying for more than 1gbit.
While this overprovisioning can be the case with any plans under 1gbit, If your ethernet card in your computer is only connected at 1gbit, then it can’t go any faster than 940mbit/s. If your gateway and PC both support & connect at 2.5gbit or higher, and your ISP has the uplink connected to higher than gig all the way through their plant, then maybe you could get more. Likely they are saving their multi gig switch ports for people paying for more than 1gbit.