Is underlay for artificial grass really necessary?

I have seen on TV that it is reccomended you use underlay especially when laying over bare earth or slabs as it prevents anything sharp from tearing the "grass' as you walk on it. If you are laying on smooth concrete with no gaps and it is well cleaned before hand then you may be ok.

I was always told ‘do it once and do it properly’ if you’ve been advised to have an underlay then it would be advisable to have it.

As an aside , our neighbours were hoovering their lawn yesterday! For years I thought it was real, it looks so good.

Won’t it hold water if it’s on top of concrete ?

Weeds can come through if you don't have underlay, as its woven.

Well, cancel that; I've just read the OP properly.

It sort of wrinkles without the underlay. You know how a rug on carpet always travels even with a sofa on top of it, not the whole rug but the bits that aren’t pinned down ruck up a bit.

I don’t have it myself but several people on the estate have done their front gardens and you can tell the ones that have just put it down without some sort of base. It undulates.

Thanks everyone for your thoughts - like you situpstraight I always remember what my Grandma used to say ... Don't spoil the ship for a hap'worth of tar and we were prepared to pay the extra.
However, the chap we spoke to first hadn't seen our yard.
A second chap has seen it and as we have good drainage, and the surface is very clean and smooth he has suggested we don't really need it.
It is such a small area, especially when the 'furniture' is replaced, that we have decided to go for it without underlay, but thank you again everyone for your thoughts.

I would think that if it rucks up you could always roll it up and put the underlay down at a later date.

That's a possibility situpstraight but the plan is to glue it around the edges where we feel necessary. The two benches we have are very heavy and also the little 'cupboard/shed' will be very heavy when DH puts all his junk back into it. We also have several planters but we do appreciate everyone's thoughts. Thank you everyone!

Each to his own but oh how I hate this stuff

It will make it nicer than sitting out with concrete under our feet Bluebelle - as you say not everyone's cup of tea!