That used to be the case. The new description removed any mention whatsoever to getting better items at the trader and "gain access to better trader items" was added to the daring adventure perk.
From a strict reading of the perks, better barter only reduces prices and daring adventure will improve the trader items but it is not entirely clear if this is for rewards or for purchasing. Considering the perk and the surrounding context, it would make more sense that it is only talking about quest rewards. That does not mean, of course, that this is how the game actually works.
From some very basic testing, it appears to me that the old function giving you better items for trade has been completely removed. Are you sure better barter still gives you the boost in trader options and if it does, is it now tied to trader inventory reset? The old system was not and worked in real time and since that seems to no longer be the case I assumed the entire function was just flatly removed.
You are absolutely right, they moved it
A21
<!-- *** INTELLECT:INFLUENCE_PERKS -->
<!-- *** BETTER_BARTER -->
.......
<effect_group>
<passive_effect name="BarteringBuying" operation="base_add" level="1,2,3,4,5" value=".05,.1,.15,.2,.25"/>
<passive_effect name="BarteringSelling" operation="base_add" level="1,2,3,4,5" value=".05,.1,.15,.2,.25"/>
.......
</perk>
<!-- *** DARING_ADVENTURER -->
......
<effect_group>
<passive_effect name="TraderStage" operation="base_add" level="1,4" value="10,40"/>
<passive_effect name="QuestBonusItemReward" operation="perc_add" level="1,4" value=".05,.20"/> <!-- Bonus Dukes -->
<passive_effect name="QuestRewardChoiceCount" operation="base_add" level="4" value="1"/>
........
</perk>
A20
<!-- Influence Perks (Intellect) -->
<perk name="perkBetterBarter" parent="skillIntellectInfluence" name_key="perkBetterBarterName" desc_key="perkBetterBarterDesc" icon="ui_game_symbol_barter">
.......
<effect_group>
<passive_effect name="BarteringBuying" operation="base_add" level="1,2,3,4,5" value=".05,.1,.15,.2,.25"/>
<passive_effect name="BarteringSelling" operation="base_add" level="1,2,3,4,5" value=".05,.1,.15,.2,.25"/>
<passive_effect name="SecretStash" operation="base_add" level="3,5" value="3000,5000"/>
Which I find makes absolutely no sense in game terms. You perk into Better Barter to improve on your buying and selling from the traders while Daring Adventurer is to improve your questing with the trader. TraderStage is tied to the tiers of gear offered by the traders for sell while quest rewards are tied into a different system.
Old method (A20 or earlier)
- Improving trader interactions for buying/selling - Better Barter only
- Improving trader interactions regarding questing - Daring Adventurer only
A21
- Improving trader interactions for buying/selling - Better Barter and Daring Adventurer
- Improving trader interactions regarding questing - Daring Adventurer only
That probably explains why I haven't seen much of a boost from Better Barter in my current playthrough - Initially I thought it was only because I am only at Level 1 in the perk but apparently I am not getting any bonus to loot stage from it.
To me, this would be like having to perk into From the Shadows to increase stealth damage bonus instead of Hidden Strike.