Supermarket Trundlers relating to the areas of Staff welfare, Safety and operational efficiency:

I have noticed that when supermarket trundlers/trolleys are being returned from the various collection ports to the store entrance ways, they are raked together and moved as one unit (rake). Now a trundler on its own is manoeuvrable because of having the two front wheels free to pivot much as the setup of many cars. This is not the case when a number of trundlers are in a rake. Although half the wheels are free to turn the rest are fixed in a straight in-line position. This negates any manoeuvring advantage given to a single trundler. To negotiate a change of direction between collection point and store front, the staff person retrieving them must resort to either; many small back-and fro movements, tilting the rake slightly onto the wheels of one side, dragging the front end of the rake round the bend or disconnecting the rake to move each trundler individually.
All these methods risk damage, personal injury or inefficiency.

One answer might be to convert all trundlers to a design used in the UK where all four wheel are pivot-able but this may not be feasible. - A better solution (and the one I recommend) is to introduce a slight tweak in the trundler design so that as they are pushed together at the collection points, each pair of rear wheels are lifted clear of the ground. That way the rake would ride on the front wheels only and thereby be easily become manoeuvrable.