Maybe the single males you know wouldn’t know if a woman got a professional manicure, but if a male grew up in a household where the women were fashionistas , his mother/sisters got their nails done every week he’d notice.
Certainly my sons and grandsons would notice how lovely a girls hands were and that the nails were nicely shaped and painted evenly.
Single women may do their hair for every day life such as school/seminary or work, but for special occasions, and meeting a potential husband should be special, a trip to the hairdresser for a special style may be in order.
My two youngest daughters were married 14 months apart. They are the same size and often shared clothing. They never shared jewelry and never borrowed. From the time they became B’nos Mitzvah they received jewelry as gifts from family members for Birthdays, graduations, etc. Occasionally, they might buy a piece for themselves.
As for your theory that a girl could wear the same outfit for every first date, you never lived in a dorm. No girl wants to kidded by her dorm-mates observing: ‘Soraleh is going on a date, she’s got in her Black Calvin Klein and the Beverly Feldman Pumps, again.’