Good thought, but I'd say your list is OTT as "essentials" especially things like jerry cans, booster pack, tow rope, trolley jack. Sure, they are nice to have, but I definitely wouldn't feel I'd have to go out and buy that lot before I did a trackday. Genuine essentials for me would be:
Oil
Coolant
Tyre pressure gauge (can always up pressures at a local garage afterwards)
Torque wrench + wheel brace
Locking wheel nut key!
Jump leads (maybe)
Gaffa tape/Zip ties
but I can see why lots of people would be more relaxed.
Although I always bring basic tools, I've never used them at a UK trackday. There's a very limited amount I could do in a pit garage/car park anyway - perhaps bleed brakes? Used zip ties/trolley jack/scissor jack to jury rig an exhaust on my Alfa to get me home from the 'Ring, and jump leads on the same trip.
In terms of a comprehensive list I'd add WD40 (v.useful to freeling off seized fastenings) and coolant, and ditch the booster pack and pack some jump leads.
Quite a personal thing though, as I say
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