​Lisa asked a good question. With inexpensive tefillin, often times you have to rely on various leniencies in terms of the kashrus of the writing, i.e. according to some opinions a certain letter may not look clear enough, whereas according to others it will. Once you get up to the level of parchments used for Tefillin Gassot, you no longer are in the realm of those types of questions, rather it’s a matter of aesthetics.

The Torah tells us Zeh Keli V’anvehu, which the Sages interpreted to me that we should fulfill mitzvahs in an aesthetically pleasing manner. For example, a nice mezuzah.

For many Jews, a nice mezuzah means a nice mezuzah case. That might be part of the mitzvah, but the essence of the mitzvah of mezuzah is the parchment; in theory you don’t even need a case at all to fulfill the mitzvah. So how do you do the essence of the mitzvah in an aesthetically pleasing manner? You find a sofer who takes his time to write nicely and who was graced with attractive writing. Sofrus is, on one level calligraphic arts. Some sofrim simply write beautiful letters.

An very inexpensive mezuzah looks a bit sloppy even to the untrained eye. To churn out $25 mezuzahs you have to write fast, so the letters do not come out very straight and the left margin is not neatly justified (it’s not easy to justify the left margin when writing by hand).

This applies equally to tefillin. Even though we cannot see the parchments after they are inserted, it’s a hiddur mitzvah to have beautifully written parshiyos in your tefillin.

Sofrim show their writing to dealers, and can command a price in accordance with the attractiveness of the writing, and that cost gets passed on to the end consumer.