They can be, but this isn't something that needs to be a big worry. The ESP drive contains the boot loaders or kernel images for all installed operating systems, and the device driver files for hardware devices that are used by the firmware at boot time. There will also be system utility programmes that run before an operating system is booted. The error logs will also be there.
Irritating that it isn't hidden, yes, but it shouldn't loom large in your life -just ignore it.