Why almost every command is trying to read urandom?

In a recent kernel(5.x) / rootfs for an embedded system (mips/MT7628/busybox, if it matters) I see TONS of:

random: mount: uninitialized urandom read (4 bytes read)
random: fsck.vfat: uninitialized urandom read (4 bytes read)
random: tar: uninitialized urandom read (4 bytes read)
...

This stops when, after a while (~10min!!) I finally see:

[  562.001438] random: crng init done

Two questions:

1. why does it take so long to initialize /dev/urandom?
2. for what reason mount or tar should try to use it in the first place?

Note: I did NOT have this problem with older kernels (3.x).