Sharing a pricelist seemed appropriate here, my Thai girl also did let me know that all taxicompanies should have fixed/same prices. Tuktuk's are almost always more expensive but more fun for some. If traveling alone a motorbiketaxi is always cheap for short distances. Grab prices should not be much different.
My gf grew up in Bangkok buy now lives in Phuket, over there we always use grab instead of a regular taxi.
Thai do not tip for this reason, a taxi should by law always use his meter and when you got inside they are not allowed to refuse your trip. Why tip somebody to thank them for not scamming you? 🤣🤣