Tim W writes

After some unreliable outside germination and also cats digging up seeds and
small seedlings I have taken to planting in cells in a plastic tray or in
peat pots. It's only a small veg patch for fun so only small quantities.
Then as soon as I think I can I put them in the ground. Spinach, runner
beans, sweetcorn, lettuce, beetroot, courgette. what's the alarm about baby
plants? Pricking out is another thing I don't really follow. I try to get
the whole lump of compost out with an old teaspoon and stick it in a hole.
Is that wrong too?

Depends how many plants are in it. Lots of plants crammed together
aren't going to grow as well as the same number of plants spaced out -
they're competing with each other for food and water. Lots of plants
crammed together probably won't even grow as well as one single plant.
So if you don't want to prick out, and you're not growing a lot, either
plant single seeds or discard all but one seedling.

Courgettes - try planting one or max 2 seeds per cell. Too many, and
they won't grow into a big enough plants to start cropping. Radishes,
for example, won't develop at all if too close - they'll just go
straight to flower without producing a radish. Runner beans - you are
probably OK with 3 to a cell and planting in one batch. Lettuce - lots
of plants together will not develop into a big hearted lettuce - let
them grow together awhile, then remove most of the seedlings and eat
them, and leave one to grow into a 'proper' lettuce.

But best thing to do is to challenge the rules and observe the results.
That way you'll learn what's best for you and your conditions.
--
Kay