09-23-15: Mitch2Mitch2, there cannot be a standard in audio for providing 1 or 2 pairs of binding posts on a speaker because cross-over design is not a cut-and-dry process where every manuf will have the same circuit. Cross-over design is complicated & full of trade-offs (such as rapid response decay & good transient response). Each speaker designer is going to choose a slightly different set of compromises that will result in a different cross-over circuit & a different sonic signature. The way the cross-over circuit is designed will have a large bearing on whether the speaker designer want the cross-over to "see" the low impedance of the amplifier (parallel cross-over topology) or to "see" the impedance created by the other cross-over elements (series cross-over topology). In the series cross-over topology the designer might not want you messing with 2 pairs of speaker binding posts that changes the impedances of the cross-over connected to the various drivers - he will want full control of this by ensuring that the signal comes in at one point & then fans out into his cross-over with controlled impedances (by his selecting the value of L or R or C per his calculations) at each node.
It sure would be easier if there were "standards" in the audio world, like providing only a single pair of binding posts on speakers.
Cross-over design is art + science & many compromises to the final result. There can be no standard when such is the nature of the problem.