They're not exploiting anything, they didn't choose the names for cellular or WiFi technologies. At worst they'll say 5G instead of 5 Gigahertz but they're not attempting to confuse or conflate anything.
Think of your internet connection like the water coming into your home. Your 2.4Ghz connection is like the water dispenser on your refrigerator, and 5Ghz is like the hose bib on the outside of your house. If the water authority says the water pressure is enough to fill up a 5 gallon bucket in 1 minute, someone will call up complaining that it takes 20 minutes to fill up a 5 gallon bucket from the water dispenser on their refrigerator.
Your ISP telling you to use your 5Ghz Wifi to test, is like the water authority telling you to test with the hose bib on the outside of your house.
Think of your internet connection like the water coming into your home. Your 2.4Ghz connection is like the water dispenser on your refrigerator, and 5Ghz is like the hose bib on the outside of your house. If the water authority says the water pressure is enough to fill up a 5 gallon bucket in 1 minute, someone will call up complaining that it takes 20 minutes to fill up a 5 gallon bucket from the water dispenser on their refrigerator.
Your ISP telling you to use your 5Ghz Wifi to test, is like the water authority telling you to test with the hose bib on the outside of your house.