In article ,
Vir Campestris wrote:

If you have a tripod ladder with well spread legs it will be stable on
any piece of firm, near level ground.

Unless the ground is absolutely level, it will lean, and THAT is the
form of instability it is twice as prone to (relative to its base
dimensions) as a tetrapod ladder. Even a slight lean is a worse danger
than most people realise, because it will put extra weight onto the
downhill legs and, if the ground is not absolutely solid, that will
cause the ladder to lean further as the user climbs it. Quite often
suddenly and unexpectedly.

If tripods did not have a serious disadvantage over tetrapods, they
would have replaced the latter millennia ago, because they are simpler
to make, lighter and (as you say) easier to position.


Regards,
Nick Maclaren.