Not having looked at the cars, the general principle is a road car bush should be compliant - ie no free play, but able to move/be deformed by road shocks. Pulling on it by hand should produce no movement. A race car though will have firmer bushes, even metal joints to give sharper responses at the expense of ride quality.
I've never heard of a correctly assembled road car wearing out the suspension bushes before a high mileage is attained and I've not yet heard of any five speeders in this bracket yet.
My guess is a batch of sub-standard parts, but 'shrugs shoulders' who knows? Do tell when you've found out!
