In 5e, healing is very inefficient and resource intensive. This is by design, and it's not a bad choice.

DnD's designers have struggled with healers since very early on. A regular complaint with 1e/2e was that "healer" characters would have to spend all their spell slots preparing healing spells, then they couldn't really "do" anything else... "healers" were viewed as no-fun classes that someone would have to bite the bullet to play anyway because you needed them.

Each edition since, they've made steps aimed at addressing this - to make healers full kits that are interesting to play with lots of options.

In 3/3.5e the main thing they did was the introduction of converting spell slots into healing - so you didn't have to prepare your heal spells into slots, you could just convert them. This gave healer characters the flexibility to prepare utility and combat spells for fun without sacrificing on healing ability. It sort of worked, but you still had to use a lot of your resources on healing.

In 4e, they introduced "healing surges" to restrict the total amount of healing that each character could receive - then they made the basic healing powers completely separated from other powers, so they didn't use the same resources. Healing in combat was limited and generally used minor actions rather than standard actions - meaning that you could "heal" people and still get to play the rest of the game at the same time.

5e returned to 3.5e's "prepare spells" model, but instead of preparing specific spells into each slot, you now just prepare a list of spells for the day, and can use any of them in any slot that's big enough - a big improvement for flexibility, because you can prepare some utility, some combat, and some healing spells, then as the day goes on, use whatever is important in the moment without wasting any spells - so because of this you don't really need "spell conversion" any more. Healer classes tend to prepare about 1/3 - 1/2 of their slots on healing and "fix condition" spells, then the rest on what they want to do (be that combat or utility etc.)

However, while this does give healers the option to prepare for all sorts of different stuff, the return to healing spells being an action (or locking you out of using your action for a leveled spell if you use HW) still had the potential to lead back into the original problem. Combat starts, and the healer character spends each of their turn just vending hitpoints. How do you address this?

The answer is pretty easy: Make "in-combat healing" very inefficient!

5e DnD parties can take quite a lot of damage in a round - especially as combats are often only a small number of rounds. Against a caster or a boss, it can be over half of the party's entire HP total in a single action... If your healer spends their turns casting healing spells they're returning only a small portion of that back to the party... it both drains your spell slots, and your actions, while failing to remotely keep up. It's almost always "better" for you to defeat an enemy fast than it is to try and mitigate whatever they're doing. Put another way, if you kill the boss one round earlier, you save multiple actions/spells worth of damage.

To compensate for the lack of good in-combat healing you make "out-of-combat" healing more efficient. Spells like "prayer of healing" vend a lot of hitpoints (but can't be used in combat because they take too long) and the "hit dice" pool of natural healing for resting is very large, especially when you buff it with feats or a bard. Parties are heavily encouraged to heal outside of combat, because it saves so many spell slots - and in-combat they're encouraged to save healing abilities for emergencies like a character going down.

If you ever wondered why "drink a healing potion" is an action, it's this. The designers want you to feel threatened by danger, but also heroic by doing cool stuff, and thus they're trying to make "stop and heal yourself" the least enticing option to pick.

Given the muggers aren't exactly "trustworthy" at this point, it's unlikely Konsi would sit down in an alley with them for 10 minutes to cast prayer of healing, if she even had it prepared at all, given her "dating" spell list - so it's likely you can infer from this exchange that she burned through a lot of spell slots to fix them up.