Traction battery stays at 2 bars

Not sure I've ever noticed my traction battery charge level displayed as bars but it sounds like both your 12v and traction battery were discharged. A discharged traction battery is common as dealers typically don't charge up Primes sitting on the lot or after test drives.
Assuming my assumptions are correct, what you are seeing are normal.
The traction battery will only recharge through regeneration or overtly putting the car in charge mode as Tideland Prius has said.
Hopefully the car comes with the home charging cable which you can use to get the traction battery fully charged and going forward use the EV mode of driving.
As for a discharged 12v battery I consider this rather normal if the car sits undriven for more than a few weeks or even less.
Enjoy your Prime.
J

 

Yep, plug it in.... 4 - 5 hours on 110VAC or 2.5 hrs on a 220VAC level-2 charger.

If that doesn't work, hopefully you can take it back. There's a 8 year, 100K mile warranty on 2018 traction packs, I believe.

 

Who would sell a plug-in car without a charge cable?!

It would be like selling any car without a key/fob!

The last two used cars we bought from a dealer only had one fob, but I made sure to get in writing the dealer would provide a second fob with the deal. With the most recent purchase, it took literally months to have them follow through after the salesman dropped the ball and subsequently left the dealership! I had to go back to the used car manager in person only to find he left also, so written documentation is a must.

This same dealer charged me $400 for a LoJack that was never installed, so more trips to the sales manager to get them to refund the $400. I guess they figure most buyers would never question or follow through with complaints. Fortunately, I'm retired and have nothing but time for these shenanigans.

 

On a used car sale? More often than you'd imagine.
Check the forums. Maybe not without any key fob but certainly with only one.
Fortunately, 3rd party level 1 charging cables are not overly costly.

 

LoL, a salesman's' worst nightmare. A customer that gets promises in writing and has all the time in the world to make the dealership follow through with their contractual agreements!!!!
Unfortunately most people who buy used cars don't carefully vet them; even new cars. I wouldn't take delivery of a car once I found the spare tire jack was missing. The sales guy literally pulled one out of another new car to close the sale. Caveat Emptor. People take things out of cars they trade-in and sell it on Facebook market place or eBay so it's not surprising the charging cable is missing. You can only get that stuff, if you notice it's missing and make it part of the sales contract.