All very well, Cherry, but if they're anything like our local supermarket, there are never enough of the small ones to go round.
What I do sometimes, if I have to use a deep one, is to put a hand-basket in the bottom, upside down, then place an upright basket on top of it for my shopping. In some supermarkets, their deep trolleys are big enough that you can fit in two pairs of baskets like this.
the thing is though the kids aren't meant to be inside the trolley but still the parents disregard the safety aspect and let the child who has legs and of an age where she or he can walk sit in the trolley,
Our local Lidl had small trolleys, of the type fitted with a pound slot. But there was a problem - with many of them it was almost impossible to get the coin back without using a pair of pliers! So they sent all the small trolleys back to where-ever as being defective, and replaced them (temporarily, they say) with deep ones. Arrrrgh. Why did they have to introduce trolleys that need a pound coin in the first place? This branch of Lidl was among the first stores in the UK to have trolleys fitted with a magnetic wheel lock system that prevents trolleys being taken off the premises!