The passage on page 219 of TNE establishes that the Imperium had travel regulations and that one of those regulations forbade steerage travel. That I have no problem with; the explanation that standard life support is rated for two people per stateroom seems to cover that pretty well. The "no steerage" rule could be "no putting people in less than half a stateroom", or it could be "no exceeding the life support limit". Personally, I'd prefer the second possibility because it allows for more differentiation (for every single occupancy stateroom you can have a three-bunk stateroom), but I can live with either option.
What does annoy me no end is the absence of rules for double occupancy passenger service. I can't fathom WHY the Imperium would have a travel regulation that prohibited double occupancy for commercial passengers, and yet the rules seem to imply just that. I can't think of any other reason why double occupancy isn't used.
And that, of course, means that generic rules, meant for places other than the Third Imperium in the Classic Era too, ought to include the option of double occupancy. Likewise, generic ship construction rules ought to include options for different levels of life support -- more or less than two per stateroom -- again to support alternate settings.
In addition to that, I would like to see Imperial travel retconned to include double occupancy passengers (Economy Passage). This could be done without causing much disruption by establishing that High, Middle, and Low passages are vouchers that can be exchanged for one trip regardless of length
1, which would allow changing per-jump pricing to per-parsec pricing without losing High, Middle, and Low passages. As for Economy Passage vouchers, no organization issues them (they may not be legal under Imperial Edict 318
2), so that's why we've never heard about any.
1 Possibly limited to 'up to four parsecs'.
2 This would be the enabling act for the issuing of passage vouchers. NB! Non-canon.
Finally, I would like to have rules that distinguish between travel by regular passenger liners and travel by free traders (e.g. people only use high passages to get on free traders in order to bump other passengers when the free trader is full up, and they don't expect high passage treatment on a free trader).
Hans