These inconsistencies are there in part because of best practices. For example, you can cut 3/4" acrylic with a 60w machine (and even a 40w probably), but its not ideal. I have a Nova 35-80 that cuts 3/4" acrylic, 2" hardwoods, 1/2" ply, 3" foam, 2x4's and more.
And sometimes our 130w machines struggle to cut 1/4" ply but that is always material, focus, optics and alignment, and settings (or a combination thereof).
Additionally, 99% of all Chinese lasers are not calibrated (tube to power supply) and may not use good quality optics so most people cannot even hold an intelligent conversation about speed and power. Thunder machines are standardized and calibrated the same way so you can have things like Material Libraries and have real solid info across the wattages.