Hmmm, I'm more than a little sceptical about that statistic. Based on the UK population, we could assume there are approximately 1m people at each age (actually this is an overestimate as the population is 63m but life expectancy 78) so the total population below the age of 5 would be 5m tops. Then I can't think that any 0 or 1 year old would have a mobile on the basis they'd eat it, so the total population aged between 2 and 4 is 3m. Which in turn means that they're saying that one in three toddlers/pre-schoolers has a phone. Really? As a mum to a four year old, a six year old and a seven year old I can vouch for not one single one of their friends/class mates having one. I've been a regular attendee of playgroups and preschool groups and I've never once seen a small child whip out a mobile phone. Many seem to get them, as others have said, when they start having to get to senior school by themselves (they tend to still be accompanied to primary school as there are no school buses and in a rural area, most live a long way away).
We do have an iPad and the children do play or watch films on that - I find it particularly useful when my youngest has to sit still and quietly for an hour while we're waiting for the boys to do karate (mostly in winter - at the moment she plays outside for the hour). Yes, I'm sure I could read stories to her for a hour but quite frankly my motherliness doesn't extend that far (a few stories yes, a solid hour, no). Other pre-schoolers do play on their parents' phones but that is not the same as owning a phone of their own.
So I'd take the statistic with a pinch of salt. Most pre-schoolers I know run around a lot, shout a lot, have imaginary friends, look at books, dress up and make up their own games just as generations and generations have done before them. And yes, I'm very grateful that I don't have to worry where the next meal is coming from - mainly because the courgettes will never stop giving - and we should all appreciate what we have and give to those who have less. But that is not an issue just for children - every single person in this society should appreciate what they have and support others who have less (wherever in the world they are).
H