Unless the speed test you are performing on these cards is somehow done wholly within the camera itself (and if so, I would love to know how you do it --seriously), the numbers are not going to be accurate.
The conditions are completely different when reading/writing to/from an SD card that, for example,
is inserted into a card reader
that is connected to a USB port
that is connected to your computer's bus
that is connected to a SATA interface (or whatever)
that is connected to an internal hard drive, etc.
The camera is designed to have a very specific and limited relationship with the recording media, and it does it very efficiently and very well to reduce latency... Far and away faster than the pathway used for testing on your computer, even if it is a laptop with a built in reader.
The test you are using is only good for maybe comparing relative differences between two or more cards, that that's about it. Don't get hung up on the numbers. Don't overthink V rating (it's different than straight up read/write speed).
The conditions are completely different when reading/writing to/from an SD card that, for example,
is inserted into a card reader
that is connected to a USB port
that is connected to your computer's bus
that is connected to a SATA interface (or whatever)
that is connected to an internal hard drive, etc.
The camera is designed to have a very specific and limited relationship with the recording media, and it does it very efficiently and very well to reduce latency... Far and away faster than the pathway used for testing on your computer, even if it is a laptop with a built in reader.
The test you are using is only good for maybe comparing relative differences between two or more cards, that that's about it. Don't get hung up on the numbers. Don't overthink V rating (it's different than straight up read/write speed).