The sowing of fine vegetable seeds must be done very carefully, so that they get into the ground evenly and not too closely.
beans, Peas and similar seeds are laid out one by one by hand. With fine seeds (Carrots, Onions) it's a bit more difficult. You can sow straight out of the bag, but have to be very careful, that not too much seed falls. The bag is held at an angle and gently shaken back and forth. That takes some practice. It's easier, Scatter the seed between your thumb and forefinger. Fine seeds are usually sown too densely. That's why it's beneficial, the seed, z.B. Carrots, mixed with the same or twice the amount of dry sand. This makes it easier to maintain the required seeding density.