The older generations are not used to devices like phones and tablets, therefore they do not have the need to use them. The other way around, the new generation is getting more technical advanced, therefore it is common for young people these days to use their phone and/or tablet often.
Also, you can see that the young people (who is supposed to have well functioning bodies) is sitting in an uncomfortable position, like their bodies has become old and tired, meanwhile the old couple’s bodies seems fresh and fit.
That way I think the photo is trying to tell us to stop wasting our lives with a phone, and should be more social and welcoming towards others, like people were back in time (maybe the artist is refereeing to their childhood to show that they miss a part of that?).