I have noticed that the umd requirements for artificer spells on scrolls are 50 percent higher than for other spells of the same spell level and caster level.
I can see the reason for the different dcs of level 6 spells like reconstruct (wiz11/sor12/art15, dc 40) and deconstruct (art15, dc 60), because reconstruct has a minimum caster level of 11 (for wizards) while deconstruct has a minimum caster level of 15, and the scrolls are caster level 11 and 15, respectively.
But I fail to see why this also applies to level 1 spells like grease and ablative armor. Grease (wiz1/sor1/brd1/art1) has a umd dc of 20, while ablative armor (art1) has a umd dc of 30. Both spells, if bought as scrolls, are caster level 1 and can be cast by the respective classes at class level 1.
The same applies to level 2 spells, for example eagle's splendor (wiz3/sor4/clr3/fvs4/brd4/pal8/art3) and elemental prod (art3): caster level 3, class level 3 (for wizard, cleric and artificer), but dc 24/36.
Is there an obvious reason for this or was this an arbitrary decision on behalf of the devs?